It's problem solving Friday - you need to log onto Mathletics and I am Thinking of a Number!
This one is all about what in maths we call inversion, also called a backwards sum.
So if I said to you, I am thinking of a number, add seven and get twenty four. What's that number?
First we need to 'translate' those words into some maths.
? + 7 = 24
Something add 7 is 24.
Next, let's get our inversion on. Turn it into a backwards sum. If we added 7 to get 24, if we take 7 from 24 we'll get that number.
24 - 7 = ?
So our number is...17
One more! I'm thinking of a number, double it and get twenty. What's that in maths...
? x 2 = 20
Work backwards - the inverse of x is ÷.
20 ÷ 2 = ?
So our mystery number is...10!
Good luck, get those thinking caps on and don't forget about that little grey 'i' on Mathletics if you get stuck.