38d — Next Prime Gap Roulette

How the readings produce a score

Each round draws two independent readings a and b, each uniformly chosen from 0 to 12. Set n = a + b + 1. Find the smallest prime p greater than or equal to n, then score p − n. If n is already prime, the score is zero: the calculation does not skip to the next strictly larger prime. For readings 0 and 0, n is 1, p is 2 and the score is 1.

Choose a Lower, Middle or Upper ticket

Choose a ticket before drawing: Lower accepts scores 0 and 1, Middle accepts 2 and 3, and Upper accepts 4 and 5. There are 169 equally likely ordered pairs of readings. Lower matches 115 pairs, Middle 51 and Upper 3. Each count divided by 169 is that ticket’s hit probability, not the probability that a session will be profitable. A matching score returns the captured stake multiplied by 0.96 × 169 ÷ the selected band’s coverage. The gross multipliers are approximately 1.410783 for Lower, 3.181176 for Middle and 54.08 for Upper. A miss returns zero. Each band’s exact expected gross return is 96%; a single round or session can differ from that average.

One stake and sequential reveals

Select a stake of 10, 20, 50 or 100 virtual coins. The default is 20 with the Lower ticket selected. Starting deducts one stake for both readings. Stake and ticket choices, restoration and another start are locked during the round; the sound control remains available. There are no extra bets, interim collection or automatic repeat rounds. The readings appear in sequence, not as two separate bets. Normally each reveal waits about 420 milliseconds. With reduced motion, each reading is revealed on its next animation frame. The second reveal completes the score and settles the captured stake. Revealing the first reading does not unlock settings or provide a collection opportunity.

Whole coins and fractional carry

The raw gross return is the captured stake multiplied by the outcome multiplier. Settlement adds the saved fractional carry to that raw return, then credits only the whole-number part of the sum. The remaining fraction is saved for later settlements. A zero-return round leaves the carry unchanged. The credited return is not a profit payment on top of a separately refunded stake.

A saved virtual wallet

The local wallet starts with 1,000 virtual coins. Balance and fractional payout carry are saved in browser local storage, including a zero balance. While idle, a balance below 10 makes manual restoration available. Restoration sets the balance to exactly 1,000 and preserves the carry; it does not add 1,000, credit the carry immediately or run automatically. Reloading before settlement ends the unfinished round without refund, payout or resumption. Its captured stake stays deducted. Previously saved balance and carry remain, while stake selection returns to 20 and the Lower ticket is selected again. Unfinished readings and chosen settings are not saved for continuation.

Site requests and adult use

The game stores the virtual-coin balance and fractional payout carry locally. Having no login or cashier does not establish anonymity or the absence of personal-data processing. The guide and demo are intended for adults aged 18 or over. This audience statement is not an implemented age check or a determination of local legality. Choose your own time and virtual-coin limit, take breaks and stop if you want to end the session. The interface does not enforce those personal limits.

Frequently asked questions