Problem – Math Game (AMC UP – 15)
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?
Check the Answer
But try the problem first…
Australian Mathematics Competition Upper Primary
2014 UP 15
Secrets of Mental Math – Arthur T. Benjamin
Try with Hints
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.
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