## Square of a 2 digit number begininning with 1

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

1. Take a 2-digit number beginning with 1(e.g., 11 to19).

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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

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What if there are more than 3 digits? Like 3 or 4 or n digits. Is there a rule then?