A maths trick to try on your family

 Amaze your audience by working out not only their age but also what size shoe they wear! Wow them even more by telling them how the maths works.

Give them the following directions but tell them not to show you any calculations:

1. Take your shoe size
2. Multiply it by 5
3. Add 50
4. Multiply by 20
5. Add 1013
6. Subtract the year you were born
7. Show me your number

The first digit is their shoe size while the last 2 digits are their age.

Did it work?

I tried it. 4 light bulb tickets on offer if you can explain why.