Squaring of numbers ending with “5” 652= 65×65=4225

But how,

There are two steps

• Put (5×5=25) in right side
• Then put {(6×6)+6}=42 in the left side
• Then we get 4225

If we have AB as a number so that B must be 5, then follow the below formula for easy remembering, AB2 = (A2+A) × 100 +B2

Example:

252 = (22+2) ×100+52

= 6×100+25=600+25=625.

Take two digit numbers say “AB” and “AC” so that, (B+C) =10, always Then, we should follow the below formula for easy remembering

AB×AC= {(A2+A) ×100} + (B×C)

Example:

42×48 = {(42+4) ×100} + (8×2) = 2016.

Let us take an example, 234×389=?

For 200, (200×300=60000, 200×80=16000, 200×9=1800, then add all the results, we get 77800)

For 30, (30×300=9000, 30×80=2400, 30×9=270, then add all the results, we get 11670)

For 4, (4×300=1200, 4×80=320, 4×9=36, the adding all results we get 1556) Now adding all the results (in bold letter) we get in the previous steps,

77800+11670+1556=91026,

This process is easier than the conventional multiplication process and we get the same answer if we directly multiply 234 with 389.

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