- Say you want to add 15 x 13. Put the biggest number on top (with your mind's eye).
- Draw the shape of Africa around the 1-5 on the top and the 3 on the bottom.
- Add these two numbers and add a zero (now we have 15+3=18, add 0= 180
- Now mulitply the digit on the bottom right (3) and the top right (5) and you get 15.
- Add the two numbers you now have (180 + 15) and you have the final answer (195).
Wednesday, July 20, 2005
Great Math Trick
I just learned a quick and easy way to multiply any two numbers from 11-19 in your head in seconds. Here's how: