A percent is a rate per 100: 25% means 25 out of every 100. A hundred grid shows it as shaded squares. To find a percent of a quantity, use the fraction: 30% of 40 is 30/100 × 40 = 12. To find the whole from a part and a percent, find 1% first, then 100%. Percents, fractions and decimals are three ways to write the same number, and the crew uses all three to read the Field Day sign-up sheet.