The rollercoaster that is professional card counting.

[RS__]

((1_hour_SD^2) * hours)^0.5

For simplicity:
((1_hour_SD^2) * hours)^0.5 = 1_hour_SD*sqrt(hours)

TBH that’s harder for me to remember. Idk why though. Kind of like when people write the formula for N0. I know there’s some super easy one, but I just set EV = SD then solve (for # rounds or # hours) from there.