A Math Forum Web Unit

Richard Briston's Math Assignments

Number Tricks - Bonus Question

_____________________________________

Question 4 - Bonus

This trick is based on the number of matches in a matchbook.

  1. Take an unused matchbook that contains 20 matches and tear out any number of matches, up to 9.

  2. Throw them away and count the matches that remain.

  3. Add the 2 digits of this number and tear out the same number of matches from the book.

  4. Tear out 2 more matches

Try this a couple of times. What is the result?

Think of a way to prove the answer will always be the same. You do not need to use algebra if you can find another method.

Student Solutions

Back to the assignment

[Privacy Policy] [Terms of Use]

_____________________________________
Home || The Math Library || Quick Reference || Search || Help 
_____________________________________

© 1994- The Math Forum at NCTM. All rights reserved.
http://mathforum.org/

Please mail comments and suggestions to Richard Briston
28 January 1996