Page 87 - Start Up Mathematics_5

1
To divide 4 by , we find how many halves are there in 4.
2

1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2

So, there are 8 halves in 4.
1 Remember
Thus, 4 ÷ = 8
2
We can also say that as there are 2 halves in 1 whole, Whole number ÷ Fraction =
there are 4 × 2 = 8 halves in 4 wholes. Whole × Reciprocal
1 number of fraction
Thus, 4 ÷ is same as 4 × 2.
2
1
2 1 1 1 1
1
1 1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2 2

To divide a whole number by a fraction:

(i) change the sign of division to multiplication.

(ii) multiply the given whole number by the reciprocal of the fraction.
1
Example 13: Divide 16 by .
4
1
Solution: 16 ÷ = 16 × 4 = 64
4
4
Example 14: Divide 20 by .
5
4 5 5
Solution: 20 ÷ = 20 ×
5 4
1
= 5 × 5 = 25

Division of a fraction by a whole number

To divide a fraction by a whole number:

(i) change the sign of division to multiplication.

(ii) multiply the given fraction by the reciprocal of the whole number.
4
Example 15: Divide by 5.
7
4 4 5 Remember
Solution: ÷ 5 = ÷
7 7 1
4 1 1 Fraction ÷ Whole number =
= × ( Reciprocal of 5 is ) 1
7 5 5 Fraction ×
4 × 1 4 Whole number
= 7 × 5 = 35

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