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Remember to use the following as guidelines:
1. Divide into groups of three. Ask your educator for the necessary paper and solve the following problems without the use of a calculator:
2. Check your answers with a calculator.
3. Compare your solutions to those of the other groups in class.
4. Discuss the differences and / or similarities between the different methods used.
There are 7 310 books in the school library. The librarian wants to put 34 books on each shelf. How many shelves does she need?
1. I calculate my answer by doing repeated subtraction .
I know 34 × 100 = 3 400.
Thus: 7 310
- 3 400 (100)
3 910
- 3 400 (100)
510
- 340 (10)
170
- 170 (5)
- - -
The answer is thus 100 + 100 + 10 + 5 = 215
2. I must calculate 7 310 ÷ 34. I do this by multiplication .
34 × 100 = 3 400, so 34 × 200 = 6 800
7 310 – 6 800 = 510
34 × 10 = 340
510 – 340 = 170
34 × 5 = 170
170 – 170 = 0
The quotient is thus 200 + 10 + 5 = 215
Thus: (3 400 ÷ 34) + (3 400 ÷ 34) + (340 ÷ 34) + (170 ÷ 34)
= 100 + 100 + 10 + 5
= 215
6. Can you think of another method to calculate 7 310 ÷ 34?
7 Explain the method used at no. 5 to your class. (Imagine YOU are the teacher!)
8. Which of the above methods do you prefer?
Why?
1. You have now looked at a variety of methods that we can use for division. Now let us concentrate on only one of them. Find the quotient of the following by using the method as applied to no. 5 on the previous page.
1.1 4 650 ÷ 25 | 1.2 5 250 ÷ 21 |
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