Expected Value

Two-outcome EV. Win and lose payoffs are net (after stake), so a fair coin flip is +100/-100.

0.52 = 52%
EV per bet
$4.00
4.0% of stake
EV per 1,000 bets
$4000.00
Long-run expectation, no variance

Math

For a two-outcome bet: EV = p · win + (1 - p) · lose

A "fair" coin flip with even payoffs gives EV = 0. A small edge means a small dollar EV multiplied by many bets — the framework's whole point is making that multiplication conscious.