XX x 1X (any number times with 10-19)
Formulas :
add 0 at the start and end of the number.
Example :
13 × 326 = 03260
Divide them to 2 in a group.
( 3 + 0 ) + 3 = 3
( 3 + 3 ) + 2 = 11
( 3 + 2 ) + 6 = 12
( 3 + 6 ) + 0 = 18
So, 13 × 326 = 4238
Formulas :
add 0 at the start and end of the number.
Example :
13 × 326 = 03260
Divide them to 2 in a group.
( 3 + 0 ) + 3 = 3
( 3 + 3 ) + 2 = 11
( 3 + 2 ) + 6 = 12
( 3 + 6 ) + 0 = 18
So, 13 × 326 = 4238