XX x XX (same tens digit, the total number of units digit is 10)

Formulas :

First 2 digits = [ __ x ( __ + 1)]

Last 2 digits = __ x __

Example :

93 × 97

First 2 digits = [9 × ( 9 + 1 )]

= 90

Last 2 digits = 3 × 7

= 21

So, 93 × 97 = 9021