Squaring two-digit numbers ending with 5

To square 2-digit numbers ending with 5:    ex.  65² = 4225

-Multiply the tens digit of the number being squared times its next higher digit. This yields the hundreds digit(s) of the answer.    ex.  The next higher digit to 6 is 7, so 6 x 7 = 42 for an answer of 42_ _.

-Because 5 is the ones digit being squared, the last two digits of the answer are always 25.    ex.  _ _ 25

Author: David

I grew up near Clayton, AL and have lived over 30 years near Atlanta, GA. My interests include family, church, guitar, gardening, working with kids... and math! Life can be very interesting. My websites: chasingtrees.net mathshortcutblog.wordpress.com View all posts by David