Envision Math 2.0: Grade 7, Volume 1
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7. Multiply Rational Numbers
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Exercise 7 Page 49

Rewrite the decimal numbers as fractions

- 48 47915000

Practice makes perfect
When multiply real numbers, the product of an integer a by an integer b is always positive if those integers have the same sign. cc Same Sign & Different Signs (+)(+)=(+) & (+)(-)=(-) (-)(-)=(+) & (-)(+)=(-) We want to find the given product. - 2.655 * (18.44) In this case one number is positive and one number is negative, so the product will be negative. Before evaluate this expression, we will rewrite the decimal numbers as fractions. We will write fractions with 1 in the denominator.
- 2.655 * (18.44)
- 2.655 * 1/1 * 18.44 * 1/1
- 2.655/1 * 18.44/1
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 1000 the numerator and denominator of -2.6551 and by 100 the numerator and denominator of 18.441.
- 2.655/1 * 18.44/1
- 2.655 * 1000/1 * 1000 * 18.44/1
- 2.655 * 1000/1 * 1000* 18.44* 100/1 * 100
- 2655/1000 * 1844/100
Now that we have the fractions, we can evaluate the product. When we multiply fractions, we need to remember that the product of two fractions is equal to the product of the numerators divided by the product of the denominators. Let's find the given product!
- 2655/1000 * 1844/100
- 2655* 1844/1000* 100
- 4 895 820/100 000
- 48 958 200/ 20/100 000/ 20
- 244 791/5000
The product is - 244 7915000. We can also write this fraction as a mixed number.
- 244 791/5000
- 240 000-4791/5000
- 240 000/5000-4791/5000
- 48-4791/5000
- 48 47915000