2 ^ (1/2 * Log2(X)) = sqrt(X) You can get a really really rough approximation if you replace Log2(x) with 'count leading zeroes'. With a better approximation

2 ^ (1/2 * Log2(X)) = sqrt(X) You can get a really really rough approximation if you replace Log2(x) with 'count leading zeroes'. With a better approximation of Log(2), you can get closer to the answer.