Put the percentage over 100 to change the percentage to a fraction. For example, if you want to convert 36 percent to a probability, put 36 over 100 to get the fraction 36/100.
Select a factor the numerator and denominator have in common. For this example, because both 36 and 100 are even numbers, divide 36 and 100 by 2 to get 18/50.
Continue to select common factors of the numerator and denominator until no common factors besides 1 exist. This reduces the fraction to its simplest terms so you can find the probability. In this example, divide 18 and 50 by 2 to get 9/25. Because 9 and 25 have no common factors besides 1, 36 percent equals a probability of 9/25, or 9 out of 25.