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Here is an alternative and more unusual version of the "Think of a Number" game which you may have heard of before.

numbers 0-9

Think of two whole numbers under $10$.
Take one of them and add $1$.
Multiply by $5$.
Add $1$ again.
Double your answer.
Subtract $1$.
Add your second number.
Add $2$.
Double again.
Subtract $8$.
Halve this number and tell me your answer.

From your answer I can work out both your numbers very quickly. How?

Try with different numbers until you see how it works and then you'll be ready to amaze your friends!

Click here for a poster of this problem.