MemoryMentor’s Blog

Finding the square of a 2-digit number beginning with 1

1. Take a 2-digit number beginning with 1(e.g., 11 to19).
2. Square the second digit (keep the carry if any)
3. Multiply the second digit by 2 and add the carry from step 2(keep the carry from this step if any)
4. The first digit is one (plus the carry from step 3)

Example:
Find the square of 13
Take the second digit and square it = 3*3=9(no carry)
_ _ 9
Multiply the second digit by 2(3*2) = 6
_ 6 9
The first digit is one 169

Find the square of 19
Take the second digit and square it = 9*9 = 81
_ _ 1(carry
Multiply the second digit by 2 and add the carry (9*2)+8 = 18+8 = 26
_ 6 1 (carry 2)
The first digit is one (plus carry) = 1+2 = 3 361