Fractions, decimals and percent
Three ways of writing the same amount. Divide to go to a decimal, multiply by 100 to go to percent.
A worked example
Write 3/8 as a percent. 3 divided by 8 = 0.375. Then 0.375 x 100 = 37.5%.
The mistake people actually make
Percent means out of 100, so 0.4 is 40%, not 0.4%.