Convert Percents, Fractions and Decimals Fractions to Decimals Part Whole 18 20 çthe line means divide 18 ÷ 20 Put the top number in the “house”; it is the dividend 18 ÷ 20 = answer Dividend ÷ divisor = quotient __.9 20√18.0 180 0 18 = .9 20 Fractions to Percents Convert 3 to a percent 5 There are two ways to do this 1. Since percents are based on 100, you can make an equivalent fraction with a denominator of 100. 3 = ___ 3 x 20 = 60 = 60% 5 100 5 x 20 = 100 _2 x 10 = _20 = 20% 10 x 10 = 100 part = __% whole 100 2. You cannot always do this, so you may have to make a decimal first. 3 8 __.375 8√3.000 24 60 56 40 40 0 = .375 decimal answer = 37.5% percent answer D è P Decimals to Fractions Millions , Hundred thousands Ten thousands Thousands , hundreds tens ones . tenths hundredths thousandths ten thousandths hundred thousandths We can make a fraction out of EVERY decimal. Write the number over its place value, then reduce or simplify (must do this). .175 number___ place value _175 ÷ 5 = _35 ÷ 5 = 7 1000 ÷ 5 = 200 ÷ 5 = 40 OR _175 ÷ 25 = _7 1000 ÷ 25 = 40 .4 write as a fraction _4 number 10 place value The 4 is in the tenths place. Now reduce _4 ÷ 2 = 2 10 ÷ 2 = 5 .15 = _15 ÷ 5 = _3 100 ÷ 5 = 20 .65 = _65 ÷ 5 = 13 100 ÷ 5 = 20 You must reduce or simplify the fraction. .375 = _375 ÷ 5 = _75 ÷ 5 = 15 ÷ 5 = 3 1000 ÷ 5 = 200 ÷ 5 = 40 ÷ 5 = 8 .05 = _05 ÷ 5 = 01 = _1 100 ÷ 5 = 20 = 20 Decimals to Percents .9 move the decimal two places to the right .90 fill in the holes with 0’s .9 = 90% A trick to remember: ABCDEFGHIJKLMNOPQRSTUVWXYZ D to P move rightè Example: .44 to percent (%) D è P .44 = 44% Percents to Decimals Move the decimal two places to the left. 85% = .85 85% A trick to remember: P to D move left ç ABCDEFGHIJKLMNOPQRSTUVWXYZ Example: 47% to decimal P ç D 47% = .47 ↵↵ OR 3.5% to decimal P ç D 3.5% = .035 ↵↵ fill in holes with zeros Percents to Fractions 75% to a fraction _75 100 then reduce or simplify _75 ÷ 5 = 15 ÷ 5 = 3 100 ÷ 5 = 20 ÷ 5 = 4 _75 = 3 100 = 4 75/100 is called a decimal fraction. 3/4 is called a common fraction. Example: 62.5% = 5 8 62.5 100 Multiply both top and bottom by 10 because there is 1 digit after the decimal place. This is to make the top a whole number. Then simplify/reduce the fraction. 62.5 x 10 = _625 ÷ 25 = 25 ÷ 5 = 5 100 x 10 = 1000 ÷ 25 = 40 ÷ 5 = 8 Example: 150% = 1 ½ 150 write down; percent is a whole number; simplify the fraction. 100 150 ÷ 50 = 3 = 1 ½ 100 ÷ 50 = 2 Finding the Percent of a Number Turn the percent into a decimal. P ç D (two places to left) Multiply the decimal number (from the percent) by the number. 87% x 68 = .87 x 68 = 59.16 Example: Find 30 percent of 400 30% = .30 .30 x 400 = 120 Repeating Decimal What if the decimal repeats? 1 3 Part Whole 1 3 çthe line means divide 1÷3 Put the top number in the “house”; it is the dividend 1 ÷ 3 = answer Dividend ÷ divisor = quotient _.3333 3√1.0000 -9 ê| | 10 | | -9ê| 10 - 9ê 10 -9 1 You write it with a line over the digits that repeat. 1 = _ 3 .33 This is called a repeating decimal. Terminating Decimal 3 5 _.6 5√3.0 -30 0 3 = .6 5 This decimal stops. It is called a terminating decimal.