Divide the fraction's numerator by its denominator to change it into a decimal. For an example, let the fraction be 1/4. So, 1/4 divided by 4, or 1 ÷ 4, equals 0.25.
Drop the percentage sign from the percent, then divide the number by 100 to convert it to a decimal. In this example, let the percentage amount be 50% --- 50 divided by 100, 50 ÷ 100, equals 0.5.
Multiply the fraction's decimal to the percentage's decimal. Concluding this example, 0.25 multiplied by 0.5, or 0.25 --- 0.5, equals 0.125.