Mathematics Magazine for Grades 112 





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.


Read more on the written version of the publication. 
