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Reciprocals

The reciprocal or multiplicative inverse of a number x is the number which, when multiplied by x , gives 1 .

So, the product of a number and its reciprocal is 1 . (This is sometimes called the property of reciprocals .)

Example 1:

3 × 1 3 = 1

so the reciprocal of 3 is 1 3 (and the reciprocal of 1 3 is 3 .)

Example 2:

4 779 × 779 4 = 1

so 4 779 and 779 4 are reciprocals.

Note that zero has no reciprocal .

Reciprocals are used to solve simple linear equations, for instance:

2 11 x = 3

To solve, multiply both sides by the reciprocal of 2 11 .

( 11 2 ) ( 2 11 ) x = ( 11 2 ) ( 3 )

x = 33 2