Squaring numbers in the 30s
 Square the last digit (keep the carry) _ _ _ X
 Multiply the last digit by 6, add the carry _ _ X _
 The first digits will be 9 plus the carry: X X _ _
Example:
If the number to be squared is 34:
 Square the last digit (keep the carry):
4 × 4 = 16 (keep 1) _ _ _ 6
 Multiply the last digit by 6, add the carry:
6 × 4 = 24, 24 + 1 = 25 _ _ 5 _
 The first digits will be 4 plus the carry:
9 (+ carry): 9 + 2 = 11 1 1 _ _
 So 34 × 34 = 1156.
See the pattern?
If the number to be squared is 36:
 Square the last digit (keep the carry):
6 × 6 = 36 (keep 3) _ _ _ 6
 Multiply the last digit by 6, add the carry:
6 × 6 = 36, 36 + 3 = 39 (keep 3) _ _ 9 _
 The first digits will be 9 plus the carry:
9 (+ carry): 9 + 3 = 12 1 2 _ _.
 So 36 × 36 = 1296.
With some practice you will be giving these squares quickly.
