NCERT Class 7 Mathematics

RATIONAL NUMBERS 189

What will be the reciprocal of

(^68) ?and?
11 5
Product of reciprocals
The product of a rational number with its reciprocal is always 1.
For example,

• 4– 4
  reciprocal of
  99
  ×⎛⎞
  ⎜⎟⎝⎠

=

–4 –9

1

94

×

Similarly,

• 6–13×
  13 6 = 1
  Try some more examples and confirm this observation.

Savita divided a rational number

4

9 by another rational number

5

7 as,

4547 28

97 9 5 45

÷ ×.

She used the idea of reciprocal as done in fractions.

Arpit first divided

4

9 by

5

7 and got

28

45

.

He finally said

45 28

97 45

÷. How did he get that?

He divided them as fractions, ignoring the negative sign and then put the negative sign
in the value so obtained.

Both of them got the same value

28

45. Try dividing

2

3 by

5
7 both ways and see if
you get the same answer.
This shows,to divide one rational number by the other rational numbers we
multiply the rational number by the reciprocal of the other.

Thus,

(^626) reciprocal of –2 6318
53 –5 3 5 210
÷ × ⎛⎞ ×
⎜⎟⎝⎠
TRY THESE