Maths tricks

[joanbyers]

DS (who is 10) was moaning in the toy shop earlier because we were looking at toys for his sister, and so to keep him quiet I asked him 26x26, 28x28, etc., which didn't take him long, so gave him 112x112, which he said was 14 squared times 8 squared (which is true), and came up with the answer I think based on 14^2 [196] x 8 x 2 x 2 x 2.

Anyway are there any tricks to do harder mental arithmetic that I could perhaps teach him?

I've got an app on my phone that DS enjoys called 'Epic Maths Tricks'. I can't comment on it myself because he's better at maths than me so I don't get what he's doing half of the time and have to check his answers with a calculator

Does he know about adding indeces?

so 82 *82 = 8^4

He obviosly sees patterns and squared is no problem so how about square rooting and iterration.

So you know the sq root of 9 = 3 and the square root of 16 =4 so what is the square root of 12?

he has to make a guess, which will be between 3 and 4 (12 is between 9 and 16, so the squareroot will be between the square roots).

Make a gues, square it and looking at the result should your next guess be higher or lower?

If he has access to programming software he can write a small program that will do it for him. And explain how his calculator works.