Fast Percentage calculations in mind using Mental Maths: Calculate almost any percentage in your mind. Simple tricks to calculate percentages like 10%, 20%, 75% and more mentally. This is useful for ...

BRAINERD, Minn. -- Consider this math problem: Find the square root of 49, double it, minus 5, square it, subtract 1, divide by 4, cut in half, cut in half, subtract 1, divide by 2, cut in half, cut ...