1X x 1X (tens digit is 1, units digit is 0-9)

Formulas :

First digits = 1

Second digits = __ + __

Third digits = __ x __

Example :

18 × 15

First digits = 1

Second digits = 8 + 5

= 13

Third digits = 8 × 5

= 40

So, 18 × 15 = 270