Multiplying together 2-digit numbers having the tens digit the same

To multiply together 2-digit numbers having the tens digit the same:    ex.  23×21=483

-Multiply the ones digits of the numbers to be multiplied. This yields the ones digit of the answer, and there may be a carry figure.    ex. 3×1= _ _ 3

_Add the uncommon ones digits of the numbers to be multiplied. To this multiply the the common tens digit of the numbers to be multiplied. This yields the tens digit of the answer, and there may be a carry figure.    ex. (3+1)(2)=_8_

-Square the common tens digit of the numbers to be multiplied. This yields the hundreds digit of the answer.    ex.  (2×2)=4_ _

Examine:    51×52=2652       73×74=5402       16×12=192        42×44=1848

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