Squaring two-digit numbers having 5 as the tens digit

To square two-digit numbers having 5 as the tens digit:    ex.  53² = 2809

-Square the ones digit of the number being squared. This yields the last two numbers of the answer.    ex.  3 x 3 = _ _ 09

-Square the tens digit (5) of the number being squared, and to this add the ones digit of the number being squared.  This yields the first two numbers of the answer.    ex.  (5 x 5) + 3 = 28_ _.

Verify   52² = 2704    56² = 3136    59² = 3481    57² x 57 = 3249