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Dividing by decimals Mr. Johnk 2015 • 3 4 = 30 40 = 300 400 • Each of the fractions are equivalent • • 3 10 30 x = 4 10 40 10 =1 10 x 10 10 = 300 400 • Any number multiplied by 1 equals that same number! • 3 4 means 3 ÷ 4 • 3 ÷ 4 can be written 43 • So when we divide by decimals, we just multiply our divisor by 10, 100, 1,000 or some other power of ten to make it a whole number. Whatever you multiply your divisor by, you must also do to the dividend! divisor dividend The shortcut is to just move the decimal the same number of places on each number! • 64.24 ÷ 0.4 Place the decimal straight up in the ● quotient 0.4 64.24 You multiplied by 10 so the decimal is now between the 2 and 4. Now just divide 642.4 by 4! Decimal out of sight-decimal to the right! • 525 ÷ 1.25 • Should our answer get bigger or smaller? ● • 1.25 525 0 0● 4 20● 125 52500 ● -500 250 - 250 00 The answer got smaller! • However many times you move the decimal to the right on the outside, is how many times you have to move it on the inside! • How many places would you move the decimal in 76.325 ÷ 0.0357? • The answer is? • 4 places on each number. • You would need to annex a zero behind the 76325 How many places this time? 87.532 ÷ 0.31 The answer is 2 places! The 0.31 would become 31 and the 87.532 would become 8753.2!