Mental Math - Square Trick

Question 1

Square trick:

What is the trick?

Example 37^2

Answer 1

Ex: 37

Step 1: (x+a)*(x-a) + a^2
Step 2: Where a is picked such that it is the closest decile

Ex: (37+3)(37-3) + 3^2 = 40*34 + 9 = 1369

Question 2

25^2

Answer 2

625

Question 3

33^2

Answer 3

36, 36*30 = 1080,1080+9 = 1089

Question 4

89^2

Answer 4

90, 90*88 ( = 7920), 7920+1 = 7921

Question 5

24^2

Answer 5

576

Question 6

19^2

Answer 6

361

Question 7

29^2

Answer 7

841

Question 8

71^2

Answer 8

5041

Question 9

83^2

Answer 9

6889

Question 10

93^2

Answer 10

8649

Question 11

16^2

Answer 11

256