Multiply Up to 20X20 In Your Head

multiply any two numbers from 11 to 19 in your head quickly, without the use of a calculator

EX: 15*18=270

solutions:
1.choose highest number first then smallest number(18*15)

2.choose 2 digit of highest number add with single digit of (1th position)smallest number
18+5=23

3.Then multiple of ten with previous answer
23*10=230 -->(1)

4.After that multiple 1st digit for both
5*8=40-->(2)

5.finally add 1st and 2nd value
230+40=270

any doubt you can ask