Multiplication interesting tricks to solve

Solve interesting Mathematics questions using tricks for students:
 
1. 20 * 20 = 400

2. 21 * 21 = 441

3. 22 * 22 = 484

4. 23 * 23 = 529

5. 24 * 24 = 576

6. 25 * 25 = 625

7. 26 * 26 = 676

8. 27 * 27 = 729

9. 28 * 28 = 784

10. 29 * 29 = 841

 The answers of above is three digit number :

Trick :- From above we can conclude that for example
20 * 20
for digit at unit place take last digit of 20 that is 0 take square of it  which is 0
for digit at tens place take again last digit of 20 then multiply last digit with 4 i.e. 0 * 4 = 0
for digit at hundreds place take digit at tens place from 20 i.e. 2 i.e. 2 take square of it  which is 4
So answer is 400

21 * 21
for digit at unit place take last digit of 21 that is 1 take square of it  which is 1
for digit at tens place take again last digit of 21 then multiply last digit with 4 i.e. 1 * 4 = 4
for digit at hundreds place take digit at tens place from 21 i.e. 2 i.e. 2 take square of it  which is 4
So answer is 441

22 * 2
for digit at unit place take last digit of 22 that is 2 take square of it  which is 4
for digit at tens place take again last digit of 22 then multiply last digit with 4 i.e. 2 * 4 = 8
for digit at hundreds place take digit at tens place from 20 i.e. 2 i.e. 2 take square of it  which is 4
So answer is 484

23 * 23
for digit at unit place take last digit of 23 that is 3 take square of it  which is 9
for digit at tens place take again last digit of 23 then multiply last digit with 4 i.e. 3 * 4 = 12 from where carry 1 and consider only 2
for digit at hundreds place take digit at tens place from 23 i.e. 2 take square of it  which is 4 add carry to it 4 + 1 = 5
So answer is 529

and so on.

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