Sally thinks of a number, multiplies it by 2, adds 2, divides by 2 and then subtracts 2. Her answer is 2. What was her original number?
But try the problem first...
Australian Mathematics Competition Upper Primary
2014 UP 15
Secrets of Mental Math - Arthur T. Benjamin
This sum is a tricky one. You can play game with this sum too
First we can start with a diagram where the number by which we are starting is X (assume).
In Hint 1 its clear that how to solve this problem.Try this ....
But if you really want a final hint then we have to solve it in reverse.Lets See another picture.
So the answer is 3.