What a buy price is made of

A buy price of 100 times the stake looks arbitrary until it is set against the return. The price is what the game charges for one round; the return is what that round pays back on average; the gap between them is the edge, restated at the buy. Learning to hold the three figures together - price, return, maximum win - is what turns a buy from a mystery amount into a small sum a reader can check.

Desk spec

the buy price: 100.00
the buy return: 96.5%
average return: 96.50
the edge: 3.50
maximum win: 5,000.00
cap as a multiple of the price: 50.0x

The control platesample A / 1,200 extra-stake rounds, four controls

feature buy100x stakeBuys one whole round at a fixed price. The stake moves from 1x to 100x in a single decision; the return is the bought round's, not the base game's.

ante bet+25% per spinRaises the price of every spin a little and the stated chance of reaching the feature a lot. It makes a non-triggering spin dearer and can make the route to the feature cheaper.

super stake2x per spinDoubles the stake for roughly double the quoted chance. It changes the size of the bet and the variance, not the expected cost of reaching the feature.

gamble0 until a winCosts nothing to be offered, then stakes a win on a double-or-nothing. It is the only control here that can take money already won and put it back at risk.

four controls, one thing in common: each changes what a round costs, and none changes what it can return beyond the game's own mathematics.

Direct answer

A buy price is made of three figures: the price as a multiple of the stake, the return the buy publishes, and the maximum win the game allows. A 100.00 buy that publishes a 96.5% return comes back at 96.50 on average, so 3.50 is the edge on the purchase - the same edge the base game carries, restated at the buy price rather than changed by it.

the three figures that price a bought round
figure	what it is	in the sample
the price	what the game charges for one bought round	100.00
the return	what that round pays back on average	96.50
the maximum win	the most the round can ever pay	5,000.00
price minus return is the edge on the purchase		3.50

The base game and the buy carry the same edge

The figure most readers expect to move when they buy is the return, and it barely does. A base return of 96.0% and a buy return of 96.5% are two halves of the same mathematics: the base game pays 96.0% of each 1.00 spin, and the buy pays 96.5% of its 100.00 price. The half point of difference is real but small; the change that matters is the size of the amount the return is applied to. A 0.5-point improvement on a hundred-fold stake is 0.50 of expected value; the same improvement does not make the round a good buy, it makes a large bet slightly less expensive than a small one. Reading the return without the price is how a buy looks better than it is.

Price, return and edge, held together the buy price 100.00 = 100 times the 1.00 base stake the published return of the buy 96.5% average return = 100.00 x 0.965 = 96.50 the edge the game keeps = 100.00 - 96.50 = 3.50 the base game for comparison 96.0% a 1.00 spin returns 0.96 on average the edge on the spin 0.04 the edge rate is nearly the same; what changed is that 3.50 is now exposed on one decision instead of 0.04 across a hundred of them so the buy is a stake multiplier, not a return improvement

Checking a buy price

Write the price as a multiple of the base stake, not as an amount.
Find the return the buy publishes; do not assume the base return.
Multiply price by return to get the average return.
Subtract to get the edge, and compare it with the base game edge.
Divide the maximum win by the price to get the ceiling in multiples of the price.

This desk prints invented prices and returns and names no real game or studio. Published buy returns, prices and maximum wins are set by each game and its operator and differ widely; the arithmetic here shows how to read them and is not advice on whether any price is fair.

The feature buyone round bought at a fixed price The maximum winhow a ceiling reprices the buy The numbersevery figure in one place