square of numbers in 100's

> Choose a number over 100 (START WITH SMALLER NUMBER).
> The last two places will be the square of
the last two digits (keep if any carry) _ _ _ X X.
> The first three places will be the number plus
the last two digits plus any carry: X X X _ _.

here is an Example:

> let the number be 108:
2. Square the last two digits (no carry): 8 × 8 = 64: _ _ _ 64
3. Add the last two digits to the number: 108 + 08= 116:
so 1 1 6 _ _
4. So 108 × 108 = 11664.