The wonder of Maths

Have you ever wonder how to calculate simple multiplication question without using calculator??? Well, yesterday Yan taught me a wonderful stone age calculation method...hehe~

To calculate the following equation:

13 X 13 =???

Solution:

Therefore, the answer for 13 X 13 = 169

p/s: this method only works for integers. We are still finding a way to solve 100 X 100 using this method. Can anybody figure it out???