Squaring a 2-digit number ending in 4

Steps
take a 2 digit number ending in 4.
square the 4; the last digit is 6: ___6 (keep carry, 1).
multiply the first digit by 8 and add the carry (1); the secondnumber will be the next to the last digit: __X6 (keep carry).
square the first digit and add the carry: XX__.

Example
if the number is 34, 4 x 4 =16 (keep carry, 1); the last digit is ___6.
8 x 3 = 24 (multiply the first digit by 8), 24 + 1 = 25 (add the carry): the next digit is 5: __56. (keep carry, 2).
square the first digit and add the carry, 2: 1156.
so 34 x 34 =1156.