Multiply Up to 20X20 In Your Head

In just FIVE minutes you should learn to quickly multiply up to 20x20 in your head.  With this trick, you will be able to multiply any two numbers from 11 to 19 in your head quickly, without the use of a calculator.
I will assume that you know your multiplication table reasonably well up to 10x10.
Try this:

• Take 15 x 13 for an example.
• Always place the larger number of the two on top in your mind.
• First add 15 + 3 = 18
• Add a zero behind it (multiply by 10) to get 180.
• Multiply the covered lower 3 x the single digit above it the "5" (3x5= 15)
• Add 180 + 15 = 195.

That is It! Wasn't that easy? Practice it on paper first! 

Take another example: 

15 x 16
Step1:  15+6 =21
Step2:  21x10=210
Step3: 5x6=30
Step4: 210+30=240 (answer)