Question 1

How do I calculate X percent of Y?

Accepted Answer

Divide X by 100 and multiply by Y. For example, 20% of 500 is 20/100 x 500 = 100.

Question 2

How do I find what percent one number is of another?

Accepted Answer

Divide the first number by the second number and multiply by 100. The second number cannot be zero.

Question 3

How is percentage increase calculated?

Accepted Answer

Subtract the old value from the new value, divide by the old value, and multiply by 100.

Question 4

What happens if the denominator is zero?

Accepted Answer

The calculator returns an undefined readout because percentage division by zero is mathematically invalid.