Math Shortcuts - Percentages and Decimals

• The rules for converting decimals to percents may be remembered using a variety of associations.
• Use common experiences in the association: Think of common percentages we see in our everyday lives, such as sales (50% off and 20% off) or runaway inflation rates (100% or 150%). These are big numbers. Decimals are small numbers (0.5, 0.2, 1.0 and 1.5). How do you make a large number smaller? By dividing. How do you make a small number larger? By multiplying. So to change from percents to decimals (large to small), you divide by 100. And to change from decimals to percents (small to large), you multiply by 100.
• Use alphabetic associations to remember the rules: To change from percent to decimal, you move the decimal point two places to the right. When you start with a percent you move to the right - p and r are close in the alphabet. To change from decimal to percent, you move the decimal point two places to the left. When you start with decimal you move to the left - decimal ends in l and left begins with l.

Source: Muskingum College Learning Strategies Database