Multiplying together two-digit numbers where the tens digits are the same and the ones digits added together equals 10

To multiply together 2-digit numbers in cases where the tens digits are the same and the ones digits added together equal 10:     ex. 12 x 18 = 216

-Since the tens digits of the numbers being multiplied are the same, multiply this digit times its next higher number. This yields the hundreds digit(s) of the answer.  For the ones digit of the answer, simply multiply the ones digits together.

Check these:   83 x 87 = 7221    54 x 56 = 3024    65 x 65 = 4225    71 x 79 = 5609    32 x 38 = 1216    93 x 97 = 9021    104 x 106 = 11024    112 x 118 = 13216