squaring the two digit number begining with 1

Squaring a 2-digit number beginning with 1
Take a 2-digit number beginning with 1.
Square the second digit (keep the carry) _ _ X
Multiply the second digit by 2 and add the carry (keep the carry) _ X _
The first digit is one (plus the carry) X _ _
Example:
If the number is 16, square the second digit:6 × 6 = 36 _ _ 6
Multiply the second digit by 2 andadd the carry: 2 × 6 + 3 = 15 _ 5 _
The first digit is one plus the carry:1 + 1 = 2 2 _ _
So 16 × 16 = 256.
See the pattern?
For 19 × 19, square the second digit:9 × 9 = 81 _ _ 1
Multiply the second digit by 2 andadd the carry: 2 × 9 + 8 = 26 _ 6 _
The first digit is one plus the carry:1 + 2 = 3 3 _ _
So 19 × 19 = 361.