Squaring

Main formula: (a+b)^2 = a^2 + 2ab + b^2

Side quick trick: AB^2 = 10A(AB+B) + B^2 where B is the last digit and AB is 10A+B.

Special trick for integers that end in 5:
(n5)^2 = 100(n)(n+1) + 25

Example: 75^2 = 100(7)(8) + 25 = 5625