Trick 26 : Squaring a 2-digit number beginning with 9

 Squaring a 2-digit number beginning with 9

Take a 2-digit number beginning with 9.

Subtract it from 100.

Subtract the difference from the original number:
this is the first part of the answer.

Square the difference: this is the last part of the answer.

Example:

If the number is 96, subtract: 100 - 96 = 4, 96 - 4 = 92.

The first part of the answer is 92 _ _ .

Take the first difference (4) and square it: 4 × 4 = 16.

The last part of the answer is _ _ 16.

So 96 × 96 = 9216.



See the pattern?

For 98 × 98, subtract: 100 - 98 = 2, 98 - 2 = 96.

The first part of the answer is 96 _ _.

Take the first difference (2) and square it: 2 × 2 = 4.

The last part of the answer is _ _ 04.

So 98 × 98 = 9604.