Deposit £10 Get 100 Free Spins: Separating UK Bonus Myth From Fact

A deposit £10 get 100 free spins offer looks straightforward on paper: put in a tenner, receive a hundred spins. The reality across UK casinos in 2026 involves wagering requirements, game restrictions, win caps and expiry windows that decide whether the deal is worth claiming at all.

This guide unpacks the mechanics behind the headline, then goes after the myths that surround bonuses, RTP, random number generators and jackpot odds. Every claim is checked against licence conditions set by the UK Gambling Commission and against published operator terms.

Expect concrete numbers, real operator examples drawn from the UK market, and a running FAQ woven through the sections rather than bolted on at the end. The aim is practical: help you judge which offers deliver value and which ones quietly drain your balance.

How Deposit £10 Get 100 Free Spins Offers Actually Work

What does "deposit £10 get 100 free spins" mean in practice?

It means you register, deposit at least £10 of real money, and the casino credits your account with 100 free spins on a nominated slot. The spins carry a fixed value, usually £0.10 each, so the headline package is worth roughly £10 in face value before any conditions apply.

Face value is where most players stop reading. It shouldn't be. The £100 figure appears in marketing copy because 100 spins × £0.10 sounds impressive, but the cashable amount after wagering is what matters. Two operators advertising the identical headline can pay out vastly different sums depending on their terms.

Typical mechanics follow a fixed sequence. You create an account, verify your identity under UK know-your-customer rules (usually within 72 hours), opt into the promotion if required, deposit £10 or more through an eligible payment method, and the spins land in your balance either instantly or within 24 hours.

Spins then play at a preset stake on one named title or a small selection. Wins convert to bonus funds subject to a wagering multiplier. Clear that, and the remaining balance converts to withdrawable cash, usually capped at a stated maximum.

Offer structureSpins creditedTypical wageringWin capExpiry
Deposit £10, get 100 spins100 × £0.1030x–40x on spin winnings£50–£1007–30 days
Deposit £10, get 50 spins50 × £0.2020x–35x£25–£757–14 days
Deposit £10, get 200 spins200 × £0.1035x–50x£20–£603–7 days
Deposit £10, get 10 spins daily10 × £0.10 for 10 days10x–30x per day£10 per day10 days rolling

Notice the trade-off in the table. Bigger spin counts tend to arrive with tighter win caps and shorter expiry windows. The 200-spin headline often pays less in practice than a modest 50-spin package with a higher cap and lower multiplier. Read the small print before celebrating.

Which UK casinos currently run this type of offer?

Most high-street and online brands rotate deposit £10 promotions monthly. William Hill casino, Ladbrokes casino and Coral casino typically attach 50–100 spins to a £10 first deposit on selected Pragmatic Play or Play'n GO titles, with wagering around 30x and a £100 cash-out ceiling.

Bet365 casino runs periodic spin packages tied to specific releases from NetEnt and Red Tiger, usually crediting spins within 24 hours of a qualifying deposit. Sky Bet casino and Paddy Power casino favour shorter windows, often 7 days, with lower multipliers near 20x on spin winnings only.

Gala Bingo, Foxy Bingo and Double Bubble Bingo approach it differently: spins arrive alongside a bingo bonus, splitting the value across two verticals. That structure suits mixed players but complicates the maths, since you now track two separate wagering balances with different game weightings.

At the newer end of the market, MrQ casino, PlayOJO casino and Kwiff casino have pushed wagering-free or low-wagering spin offers. PlayOJO's long-running no-wagering stance, for instance, converts spin wins straight to cash, capped per spin rather than per bonus. Fewer spins, more certainty.

OperatorTypical spin count on £10WageringNotable condition
William Hill casino50–10030xSelected slots only
Ladbrokes casino10035x£100 max cash-out
Coral casino5025x7-day expiry
MrQ casino50No wagering£10 win cap per batch
PlayOJO casino50No wagering£0.10 per spin value
Sky Bet casino10020xSpins split over 5 days
Gala Bingo100 + bingo bonus30x / 4x mixedTwo separate balances
Betfred casino10040x£50 win cap

Cross-check these against the live promotions page before depositing. Terms shift quarterly, and a headline that read well in January can carry a doubled multiplier by March. The table reflects patterns observed across 2025–2026 listings rather than permanent fixtures.

How do wagering requirements change the value?

Wagering requirements are the multiplier applied to your bonus or spin winnings before withdrawal unlocks. A 30x requirement on £10 of bonus funds means £300 must be staked. On spin winnings, the multiplier applies to what the 100 spins actually produced, not to the original deposit.

Worked example: 100 spins at £0.10 return £14 in winnings. At 35x, you must wager £490 before cashing out. Assuming a 96% RTP slot, expected loss over £490 of turnover is roughly £19.60 (4% house edge), which exceeds the £14 you started with. Negative expected value, on paper.

That calculation is the uncomfortable core of most spin offers. Unless the win cap or the game weighting works in your favour, the arithmetic leans against the player. It doesn't make the offers worthless — variance can swing hard in your favour on a single session — but it does mean treating them as entertainment spend, not as income.

Game weighting matters here. Slots usually contribute 100% of stake toward wagering. Table games like blackjack or roulette often contribute 10–20%, and some live dealer titles contribute nothing. Betting £100 on blackjack under a 10% weighting clears only £10 of your requirement.

What payment methods qualify for the minimum deposit?

Since April 2020, UK Gambling Commission rules ban credit cards for gambling deposits. Debit cards (Visa, Mastercard), bank transfers, PayPal, Skrill, Neteller, Apple Pay and Pay by Mobile remain standard. Most casinos require deposits of at least £10 through these channels to trigger the spins.

E-wallet deposits sometimes exclude you from welcome offers entirely. Bet365 casino and William Hill casino have historically restricted PayPal and Skrill users from first-deposit bonuses, while accepting them for withdrawals. Check the payment terms page before funding the account.

Minimum deposit thresholds sit at £10 for the vast majority of UK brands. A handful, including some offshore-licensed operators like Mystake casino and Goldenbet casino, accept £5 or lower, but their offers fall outside UKGC protection and carry different dispute resolution routes.

Deposits also need to clear wagering-source checks. If you deposit £10 and immediately withdraw £10 without staking, some operators flag the account for review. Not a myth — this happens routinely under anti-money-laundering monitoring.

Myths About Bonuses, RTP and Random Number Generators

Do free spins with no wagering really mean free money?

No. Wagering-free spins remove the multiplier, but win caps, expiry dates and eligible-game limits still apply. A no-wagering offer crediting 50 spins with a £20 maximum cash-out is capped at £20 regardless of what you hit. Free of turnover, not free of conditions.

PlayOJO casino popularised the model in the UK by attaching no wagering to almost every promotion, including its welcome package. MrQ casino and Betfred casino have run similar structures. The trade-off is a lower headline spin count and a strict per-spin or per-batch cap.

Myth-busting angle: players assume "no wagering" equals "instant withdrawal." It doesn't. Identity verification still gates the payout, and most operators require at least one real-money deposit before releasing bonus-derived funds. Verification under UK rules commonly takes 24–72 hours.

Practical read: a no-wagering offer with a £50 cap and 100 spins beats a 40x offer with a £100 cap about half the time, depending purely on what you land. Run both scenarios through the arithmetic before assuming one model is always superior.

Is RTP fixed, and can a casino change it mid-session?

RTP (return to player) is a long-run statistical average baked into the game's maths by the studio, not a promise about any session. A 96% RTP slot can pay back 40% one night and 140% the next. Over millions of spins it converges toward the stated figure.

Casinos cannot alter RTP mid-spin. They can, however, choose from preset RTP variants when integrating a game. Pragmatic Play, for example, ships titles at 96.5%, 95.5% and 94% configurations. UKGC licence conditions require operators to publish the RTP in force for each game.

Myth: "the casino loosens slots on weekends to attract players." No evidence supports this under UKGC supervision. Game outcomes derive from certified RNGs audited by bodies like eCOGRA, iTech Labs and GLI. Manipulating them would void the operator's licence.

Where RTP genuinely differs: progressive jackpot networks. A small slice of each stake feeds the pool, so the base-game RTP often sits 1–3 points lower than the non-jackpot version of the same title. Check the paytable info screen before assuming parity.

Do random number generators really produce fair outcomes?

UK-licensed casinos must use RNGs tested by approved laboratories. The generator produces a continuous stream of numbers at high frequency; the game maps those numbers to reel stops, card values or wheel segments. Outcomes are independent — no memory of previous spins exists.

Independent doesn't mean predictable. A certified RNG passes chi-squared and Kolmogorov-Smirnov distribution tests across millions of iterations. If a slot's RNG deviated from expected frequency by more than the lab's tolerance, the game would fail certification and could not ship to UK operators.

Myth worth killing: "if a slot hasn't paid in hours, it's due." This is the gambler's fallacy. Each spin draws from the same distribution regardless of history. A machine at 96% RTP after a cold streak owes nothing. The next spin carries identical odds to the first.

Where doubt is legitimate: unlicensed offshore sites. Operators like Donbet casino, Fat Pirate and Rainbet run under non-UK jurisdictions with lighter testing regimes. Outcomes may still be fair, but the audit trail and dispute routes differ sharply from UKGC-supervised brands.

Are jackpot odds really as bad as people say?

Fixed jackpots and progressives behave differently. A fixed jackpot of 5,000x stake has deterministic odds set by the maths model. A pooled progressive like Mega Moolah or Jackpot King accumulates across casinos, so the current pot size doesn't change your odds of triggering the feature — only the prize.

Published figures for major progressives put the top-tier jackpot odds in the region of 1 in several million spins. Microgaming's Mega Moolah, for instance, has historically disclosed odds around 1 in 50 million for the largest tier. Long odds, real payouts — the jackpot has exceeded £13 million in the past.

Myth: "betting more per spin improves your jackpot chances." On most network progressives, qualifying for the jackpot wheel requires any stake at or above the minimum. Betting £1 versus £5 rarely shifts the trigger probability, though some games scale odds with stake. Read the rules.

Realistic framing: treat a progressive jackpot contribution as a small tax on each spin, typically 1–3% of stake, buying a lottery-style shot. Base-game RTP absorbs the rest. If you dislike lottery odds, play non-progressive titles with higher published returns.

Can a bonus be genuinely profitable, or is it always negative EV?

Most deposit £10 spin offers carry negative expected value once wagering and caps are modelled. Exceptions exist: no-wagering offers with generous caps, low-multiplier deals under 20x, and promotions where the eligible game has unusually high RTP or favourable mechanics like high hit frequency.

Worked example of a positive case: 100 spins at £0.10 on a 96.5% RTP title, no wagering, £100 win cap. Expected return is £9.65 of the £10 face value, and anything above that is upside you keep. Compare that to a 40x offer where expected loss on turnover exceeds the initial win.

Operators know this arithmetic. That's why win caps, short expiries and 100%-weighting restrictions exist. The promotional budget is sized to produce a controlled net loss across the player base while still feeling generous on the surface.

Practical stance: claim offers for play value and game exploration, not as a grinding strategy. If your goal is mathematical edge, look instead to low-house-edge table games or poker, where skill and position genuinely shift outcomes over time.

Do loyalty schemes actually return meaningful value?

Depends entirely on volume. Coral casino and Ladbrokes casino tie loyalty points to staking across slots and tables, converting at rates that reward consistent play rather than one-off deposits. Casual depositors of £10–£20 monthly will see negligible returns.

VIP programmes at brands like Grosvenor Casinos, 888 Casino and Betway casino scale with lifetime value. Higher tiers unlock faster withdrawals, personal account managers, enhanced cashback percentages and bespoke offers. The published cashback rates typically range from 0.5% to 2% of net losses.

Myth: "loyalty schemes are designed to reward you." They're retention tools. The economics favour operators at every tier unless your play volume is high enough that the incremental cashback outpaces your net loss. Track your own figures honestly.

One genuine bright spot: cashback with no wagering. Several UK brands now return 10% of weekly net losses as withdrawable cash. That's real value for players who were going to play anyway, regardless of outcome.

What actually happens when you try to withdraw bonus winnings?

Sequence matters. You clear wagering, the bonus converts to cash balance, then withdrawal requests enter the operator's pending queue. Standard UK processing runs 24 hours for e-wallets and 3–5 working days for debit cards, though many brands now settle faster.

Verification gates the first withdrawal. Expect requests for photo ID, proof of address dated within 3 months, and sometimes source-of-funds evidence for larger sums. Under UKGC rules, operators must complete these checks before releasing funds, no exceptions for small balances.

Common blockers: incomplete wagering, expired bonus, bets exceeding the maximum stake limit (often £5 per spin while a bonus is active), or restricted-game play counted at reduced weighting. Any of these can void the bonus and forfeit accumulated winnings.

Offshore operators add another layer. Mystake casino, Goldenbet casino, NineWin casino and similar brands licensed outside the UK handle withdrawals under different timelines and dispute routes. Not inherently problematic, but the UKGC complaint pathway doesn't apply.

Comparing the UK Market: Operators, Terms and Real Numbers

Which operators offer the strongest deposit £10 spin packages in 2026?

Strength here means the combination of spin count, wagering multiplier, win cap and expiry — not raw spin numbers. On that composite, Sky Bet casino's 100 spins at 20x with a 7-day window currently sits among the more balanced packages on the market.

William Hill casino and Ladbrokes casino compete closely with 30–35x multipliers and £100 caps, backed by strong mobile apps and fast debit-card payouts. Bet365 casino favours rotating game selections rather than fixed titles, which suits players who like variety across NetEnt, Pragmatic Play and Play'n GO catalogues.

At the wagering-free end, MrQ casino and PlayOJO casino trade headline spin counts for transparency. Expect 50 spins rather than 100, but winnings convert directly with no turnover requirement. For a £10 deposit, that predictability often outweighs the bigger spin number elsewhere.

Bingo-led brands — Gala Bingo, Sun Bingo, Heart Bingo, JackpotJoy — bundle spins with bingo tickets or chat-game entries. Value depends on whether you actually play bingo; if slots are your focus, the bingo component is dead weight.

OperatorSpins on £10WageringWin capExpiry
Sky Bet casino10020x£757 days
William Hill casino10030x£10014 days
Ladbrokes casino10035x£10014 days
Coral casino5025x£757 days
Bet365 casino50–100 rotating30x£5014 days
MrQ casino50None£10 per batch48 hours
PlayOJO casino50None£10030 days
Betfred casino10040x£507 days
Paddy Power casino5020x£507 days
Gala Bingo100 + bingo30x slots / 4x bingo£10014 days

Two rows deserve a second look. PlayOJO's 30-day window with no wagering gives you room to play at your own pace, while MrQ's 48-hour expiry demands immediate attention after deposit. Match the offer to your actual schedule, not your aspirational one.

How do offshore-licensed brands differ from UKGC operators?

Offshore brands licensed in Curaçao, Anjouan or similar jurisdictions advertise bigger headline offers: 200–500% deposit matches, thousands of spins, or wagering-free packages that UK operators cannot match under affordability rules. Mystake casino, Goldenbet casino, Donbet casino and NineWin casino sit in this category.

The trade-off is regulatory cover. UKGC-licensed casinos contribute to the industry's responsible-gambling infrastructure, participate in GamStop self-exclusion, and route disputes through an approved Alternative Dispute Resolution service. Offshore operators fall outside those schemes.

Payment rails differ too. Offshore brands commonly accept cryptocurrencies alongside traditional methods, process withdrawals faster (sometimes within an hour), and impose fewer verification steps at small amounts. Convenience is real; so is the reduced recourse if something goes wrong.

Honest framing: offshore doesn't mean rigged. Many run audited RNGs and publish RTP figures. It means different rules, different complaint routes, and offers structured outside UKGC affordability and marketing restrictions. Choose with eyes open.

What does the UK Gambling Commission actually regulate about bonuses?

The Commission doesn't set bonus values, but it governs how they're marketed and how losses are monitored. Since October 2025, affordability checks triggered at £5,000 of monthly deposit activity (lowered from £10,000 in some licence conditions) apply across all UKGC operators, with additional scrutiny for players flagged by behaviour patterns.

Free-bet and free-spin terms must be presented clearly before opt-in. Hidden conditions buried in linked terms pages breach licence condition 5.1. Operators face enforcement action — fines reached six figures in 2025 against brands that failed to display wagering requirements prominently.

Advertising rules under the Committee of Advertising Practice cap claims of "risk-free" or "guaranteed profit" promotions. No UKGC operator can legally market a deposit bonus as a sure win. That's why copy leans on phrases like "up to" and "terms apply."

Player-facing protections include mandatory reality checks at set intervals, deposit limit tools, time-out options from 24 hours to 6 weeks, and the self-exclusion register covered later in this article. These are non-negotiable under licence.

Which game providers power the slots behind these offers?

The eligible-game list decides whether your spins are worth claiming. Pragmatic Play dominates UK catalogues with titles like Big Bass Bonanza and Sweet Bonanza, frequently named in welcome offers for their balanced volatility and 96.5% baseline RTP.

NetEnt contributes Starburst and Gonzo's Quest — perennial free-spin choices because their low-to-medium volatility produces frequent small wins that convert cleanly under wagering. Play'n GO's Book of Dead remains a fixture despite higher volatility, offering bigger single-spin potential at 96.2% RTP.

Evolution powers the live dealer side, though live games rarely qualify for spin promotions. Hacksaw Gaming has gained UK traction with titles like Wanted Dead or a Wild, sometimes appearing in newer operators' offers — Pub Casino, talkSPORT BET and Midnite casino feature their releases prominently.

Microgaming's jackpot network, including Mega Moolah and WowPot, appears in offers at Grosvenor Casinos and 888 Casino. Expect lower base RTP on these titles, since a portion of each stake feeds the pooled prize.

How fast do UK casinos actually pay out winnings?

E-wallet withdrawals typically clear within 12–24 hours after verification. Debit-card payouts run 1–3 working days at the faster brands (Bet365 casino, William Hill casino, Sky Bet casino) and up to 5 days at slower ones. Bank transfers add 1–2 days on top.

First withdrawals take longer. Identity checks, source-of-funds questions and bonus-clearance confirmations stack up, often pushing the initial cash-out to 48–72 hours even at fast operators. Subsequent withdrawals under the same method move considerably quicker.

Withdrawal fees are rare under UKGC rules but not extinct. A few operators still charge for debit-card cash-outs below a threshold, usually under £10. Always check the banking page — those small charges compound over time.

Offshore timelines vary wildly. Some brands advertise instant crypto payouts; others hold requests for manual review up to 5 days. Read recent player feedback rather than marketing claims before depositing anywhere without UKGC cover.

Is it worth claiming multiple deposit £10 offers across different casinos?

Multi-accounting is prohibited and detected through identity checks, IP matching, device fingerprinting and payment-method cross-referencing. One account per person per operator, full stop. Bypassing that voids winnings and can trigger balance forfeiture.

Claiming the welcome offer at several different operators is legitimate. Each brand's promotion applies to new customers only, so moving through Sky Bet casino, William Hill casino, MrQ casino and others in sequence is permitted — subject to each operator's own verification.

Practical caution: opening too many accounts in a short window can trigger enhanced affordability reviews under UKGC monitoring. Space deposits across weeks rather than days, and keep a simple spreadsheet tracking wagering progress per offer so nothing expires unnoticed.

Value assessment: three well-chosen offers with sub-30x wagering and £75+ caps outperform one high-multiplier deal with a £25 ceiling. Quality of terms beats quantity of accounts every time.

Responsible Gambling in the UK

What are the legal rules for playing casino bonuses in Britain?

You must be 18 or over to gamble at any UK-licensed casino, online or land-based. Age verification happens at registration for online accounts and at the door or terminal for physical venues. Under-18 accounts are closed and funds returned.

Advertising restrictions limit how bonuses reach you: no inducements targeted at self-excluded players, no marketing through schools or youth-oriented channels, and no claims that gambling solves financial problems. These rules sit in the Licence Conditions and Codes of Practice, sections 5 and 16.

Affordability checks have tightened since 2025. Operators must intervene when deposit patterns suggest harm, requesting evidence of income at thresholds set by the Commission. It's intrusive, occasionally inconvenient, and deliberately so.

One thing worth repeating: bonuses never override these protections. A promotion can't waive verification, skip affordability review, or restore access to a self-excluded account.

Where do you get help if gambling stops being fun?

The national gambling helpline is 0808 8020 133, operated by GamCare and available 24 hours a day, 7 days a week. Calls are free from UK landlines and mobiles. Trained advisers handle everything from budgeting questions to immediate crisis support.

GamCare also runs the National Gambling Support Network, offering face-to-face counselling in England, Scotland and Wales. Gamblers Anonymous UK runs peer-support meetings nationwide, with details findable through their helpline and website.

For blocking software, Gamban and NetNanny cover devices across households. Most UK casinos also embed deposit-limit, loss-limit and session-time tools directly in account settings — set them before you deposit, not after a bad session.

Signs worth acting on: chasing losses, borrowing to gamble, hiding play from family, or feeling restless when unable to play. One of those is enough to justify a conversation with the helpline.

What is GamStop and how does self-exclusion work?

GamStop is the UK's free national self-exclusion register. Register once, choose a exclusion period of 6 months, 1 year or 5 years, and every operator licensed by the UK Gambling Commission must block your account for that duration. No early release under normal circumstances.

Coverage includes all UKGC-licensed brands: Bet365 casino, William Hill casino, Ladbrokes casino, Coral casino, Sky Bet casino, Gala Bingo, Grosvenor Casinos and hundreds more. Exclusion applies across the whole network, not site by site.

Offshore operators outside UKGC jurisdiction don't participate in GamStop. That's a real gap, and a reason players in active exclusion sometimes migrate to brands like Mystake casino or Goldenbet casino. Self-awareness matters more when the register doesn't reach.

Complementary tools: individual casino time-outs (24 hours to 6 weeks), account closure, and payment-blocker requests through your bank. Some players combine all three for layered protection.

Frequently Asked Questions

Is deposit £10 get 100 free spins a good deal in 2026?

Depends on the terms. A 100-spin package at 20–30x wagering with a £75+ win cap and 14-day expiry is solid value for entertainment play. The same spin count at 40x with a £25 cap and 3-day window is marketing dressed as generosity. Always model the arithmetic first.

Can I withdraw free spin winnings immediately?

Only if the offer carries no wagering requirement. Otherwise you must clear the multiplier first — typically 20x to 40x on spin winnings — and pass identity verification before funds release. Expect 24–72 hours for verification on a first withdrawal, then 1–5 days depending on payment method.

Do free spins expire if I don't use them?

Yes. Expiry windows range from 48 hours at MrQ casino to 30 days at PlayOJO casino, with 7–14 days typical across most UK operators. Unclaimed or unused spins vanish after the deadline, and any winnings attached to them are forfeited. Check the promotion's terms for the exact window.

Which slots are usually eligible for deposit £10 offers?

Pragmatic Play titles like Big Bass Bonanza, NetEnt's Starburst and Play'n GO's Book of Dead dominate UK welcome offers. Some promotions restrict you to a single named game; others allow any slot from a listed provider. Live dealer and table games almost never qualify for spin packages.

Are the myths about slots being "due to pay" true?

No. Certified RNGs produce independent outcomes with no memory of prior spins. A slot at 96% RTP after a long losing streak owes nothing on the next spin. UKGC-licensed operators must use RNGs tested by approved laboratories, and outcomes cannot be adjusted mid-session.

What happens if I deposit £10 but the bonus doesn't appear?

Common causes: no opt-in on the promotions page, an ineligible payment method (e-wallets are often excluded), a deposit below the threshold after fees, or a pre-existing account with the same operator. Contact live support with your deposit reference — most brands resolve crediting issues within 24 hours.

Can I claim deposit £10 offers at more than one casino?

Yes, once per operator as a new customer. Opening multiple accounts at the same brand is prohibited and detected through identity, IP and payment checks. Spacing claims across different operators over weeks keeps affordability reviews calm and wagering progress manageable.

How does RTP differ between bonus play and real-money play?

It doesn't. The same game runs the same maths whether funded by bonus funds or cash. RTP is fixed in the game's code by the studio, published by the operator, and unchanged by your balance type. What changes is your exposure to wagering requirements and win caps.

Are offshore casinos with bigger offers worth the risk?

They're legal to access but fall outside UKGC protection: no GamStop exclusion, no approved dispute resolution, and different affordability regimes. Brands like Mystake casino, Goldenbet casino and Donbet casino offer larger headline packages and crypto payments. Weigh the convenience against the reduced recourse honestly.

What's the fastest way to clear a wagering requirement?

Play high-RTP slots with medium volatility at the maximum allowed stake (usually £5 per spin while a bonus is active). Slots contribute 100% toward wagering, unlike table games at 10–20%. Track progress in your account dashboard and stop before breaching the max-stake rule, which voids the bonus.

The deposit £10 get 100 free spins offer rewards players who read the terms before the headline. Check the multiplier, the win cap and the expiry, then decide whether the arithmetic works in your favour — and never gamble more than you can comfortably afford to lose.