Dice

A roll is a number from 0.00 to 99.99, every value equally likely.

Choose a win chance from 2.00% to 98.00% and a side. Rolling under wins when roll < chance. Rolling over wins when roll ≥ 100 − chance.

The multiplier is 99 / chance. At 49.50% it pays 2.0000×; at 2.00% it pays 49.5000×.