Big Ideas Math: Modeling Real Life, Grade 7
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5. Dividing Rational Numbers
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Exercise 2 Page 74

To divide two decimal numbers, multiply the divisor and the dividend by the same power of 10 so that the divisor is a whole number.

5.45

Practice makes perfect
We want to divide two decimal numbers. The calculations are easier if we multiply the divisor and the dividend by the same power of 10 so that the divisor is a whole number. In this case, we will multiply by 10. - 6* 10 &= - 60 - 1.1* 10 &= - 11This means that - 6Ă· (- 1.1) is the same as - 60Ă· (- 11). Next, recall that when dividing real numbers, the quotient will be positive if the signs are the same and it will be negative if the signs are different. cc Same Sign & Different Signs (+)Ă· (+)=(+) & (+)Ă· (-)=(-) (-)Ă· (-)=(+) & (-)Ă· (+)=(-) In our case both numbers are negative, so the quotient will be positive. - 60Ă· (- 11)=60Ă· 11 Let's find the quotient! We will divide, multiply, subtract, and compare as many times as we need.
We found a pattern in the given quotient! 60Ă· 11 = 5.4545... We can write this repeating pattern as 5.45. 60Ă· 11 = 5.45 Since 60Ă· 11=5.45, we know that 6Ă· 1.1=5.45. This means that - 6Ă· (- 1.1)=5.45.