# Kangaroo Contest 2013 Talk about Cryptography

On Sunday March 24, 2013, I gave a talk on the History of Cryptography [PDF], at the University of Toronto (Scarborough) for the parents of students writing the Kangaroo Contest. I had many questions after my talk, so here are some answers to the questions I received.

### Where did you get this information?

Most of this talk came from Elementary Number Theory by David M. Burton, the Wikipedia article for RSA, and the Wikipedia article for Diffie-Hellman. As a general rule of thumb, Wikipedia is a reliable source for things of a mathematical nature (as only experts tend to edit the articles).

### My child is interested in codes, what are some resources for them to learn more?

Here is a great introduction to modular arithmetic which serves as the foundation for learning about the math of cryptography. Modular arithmetic is like “clock math”, where 4 hours after 10 o’clock is 2 o’clock.

Codecademy is a very good way to start learning computer programming. It is a very fun website and is very motivating, and fun!

DIY.org is a cool site that empowers children to become ‘makers’. It provides a bunch of resources for children to complete a variety of projects, some of which are math/computer based. I really like this site!

### What are some good resources for contest problems?

Crux Mathematicorum is a magazine published by the Canadian Mathematical Society (CMS). It contains tons of problems that appeared in Math contests across many different age ranges.

Here is a website devoted to the problems of Martin Gardner a very famous figure who posed an endless number of interesting math questions. Martin Gardner wrote the math column for Scientific American from 1956 to 1981.

### What are some ways to strengthen my child’s strategic thinking?

I firmly believe that play time and thinking time are very much the same thing for children (and mathematicians!). Some games that strengthen your mathematical thinking include the card game Cribbage, the ancient game Mancala, and the new card game Dominion.

### Do you have any articles on your blog at the same level as this talk?

Yes! Here is my article about a fun problem called “The Battery Problem” (which I found in an old copy of Crux Mathematicorum). I also wrote about a neat phenomenon with birthdays and siblings.