Mental Math - Square Trick Flashcards
1
Q
Square trick:
What is the trick?
Example 37^2
A
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
2
Q
25^2
A
625
3
Q
33^2
A
36, 36*30 = 1080,1080+9 = 1089
4
Q
89^2
A
90, 90*88 ( = 7920), 7920+1 = 7921
5
Q
24^2
A
576
6
Q
19^2
A
361
7
Q
29^2
A
841
8
Q
71^2
A
5041
9
Q
83^2
A
6889
10
Q
93^2
A
8649
11
Q
16^2
A
256
