Left digit same and Right digits total =10

Short trick:

(L2+L)|R1xR2

 

Example:

 Multiply 24 and 26

Here left digit of both 24 and 26 is 2. and sum of right digits is 10(4+6).

therefore L= 2, R1=4 and R2=6

Solution:

(L2+L)|R1*R2
=22+2|4*6
=4+2|24
=6|24
=624

 Note: if R1xR2<10  then add ’0’ before result of R1xR2.

 

Example:

Lets Multiply 91 and 99

Here left digit of both 91 and 99 is 9. and sum of right digits is 10(1+9).
therefore
L= 9, R1=1 and R2=9.

Solution:

(L2+L)|0R1*R2
=92+9|01*9
=81+9|09
=90|09
=9009