Does anyone know some number or math tricks that would fascinate a 10 year old?

Question

I'm thinking of those kinds that you figure out what number a person is thinking, but any kind of math trick would be great! thanks

Answer 1

I don't know about fascinating a 10 year old but these might cause him to have some fun:

If thirty three and a third is a third of a dollar how much is a third of a dollar and a half? (50 cents - but for some reason people always say eighty three and a third)

Is it more correct to say 5 and 6 IS 13 or 5 and 6 ARE 13 (neither 5 and 6 equals 11)

Three men go into a hotel and the owner charges them $10.00 each to spend the night. Later the owner decides he overcharged them so he sent the bell hop up with $5.00 to return to the men. On the way up the bellhop decides that he needs a tip so he takes two of the dollars and then gives each man one dollar back. So now each man has paid nine dollars each - three times nine equals twenty seven plus the two dollars the bellhop took equals twenty nine - what happened to the extra dollar?

Answer 2

Think of a number between 1 and 10.

Multiply it by 9.

Add up all the digits.

Subtract 5.

Add the original number you thought of.

Multiply by 2.

Now add 2.

Now tell me what you've got, and I'll tell you what your number was.

(Divide by 2 and subtract 5 to get the original number.)