18/100 = 18%
A value of 18% might show up as a discount on a jacket, a tip on a restaurant bill, or the share of students who choose a certain activity. It means a little less than one-fifth of the whole.
To picture 18%, imagine shading 18 squares in a grid of 100, or nearly 2 out of every 10 items. Since one-fifth is 20%, 18% is just a bit smaller.
A common mistake is to treat 18% as 18 whole items instead of 18 parts out of 100. The actual amount depends on what the percentage is being compared with, so 18% of a small bill is less than 18% of a large one.
