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4.8.1 Exercises

Perform the indicated divisions. Use the bar notation for repeating decimals. If you round off, indicate
to what place.
1. 91 ÷ 20

2. 14.68 ÷ 5

3. 23 ÷ 90

4. 86 ÷ 71

5. 6.02 ÷ 9

6. 4.19 ÷ 13
7. 804.09 ÷ 215

8. 353 ÷ 37

9. 17 ÷ 19

10. 38.8 ÷ 40

4.9 Division of a decimal by a decimal

What do we do when the divisor is a decimal? For example, how do we perform the division 8.61÷ 2.5?
The answer is simple. Just multiply both the dividend and divisor by a power of 10 sufficiently large
to make the divisor into a whole number, and then proceed as before. In this example, if we multiply
1
both numbers by 10 , the divisor 2.5 turns into the whole number 25 and the dividend turns into 86.1.
Recall that two fractions are equivalent, that is, represent the same number, if one is obtained from the
other by multiplying both numerator and denominator by the same nonzero number. In this case, the
1
convenient choice of nonzero multiplier is 10 = 10, because it turns the denominator (divisor) into a
whole number. Thus,
8.61 8.61 × 10 86.1
= = .
2.5 2.5 × 10 25
In other words, the division problem 8.61÷2.5 has the same quotient as the division problem 86.1÷25.
We do the latter problem exactly as in the previous section.

3. 444

25 86. 100
− 75
11 1
− 10 0
11 0
− 100
10 0
− 100
0

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