Clock (Modular) Arithmetic Pages
On these pages you can learn about modular arithmetic,
which is arithmetic on a circle instead of a number line.
Some of these materials have been used with current and
future teachers (elementary and middle school), and with
actual kids as young as second grade. I hope that
anyone who is interested in numbers can find something
to learn from here.
Explanations
- The
short (well, medium length) version:
What is clock arithmetic?
- [Coming soon] The long version: What is clock arithmetic?
- [Coming later] What is clock arithmetic good for?
(Hint: just ask the National Security Agency. Also see the
references below about RSA and PGP.)
Tools
- A calculator
for renaming numbers on a clock.
- A calculator
for arithmetic (+, -, x) on a clock.
- [Coming soon] A calculator for dividing on a clock.
- [Coming soon] A calculator for exponentiation on a clock.
- An encoder for secret message"code.html">encoder for secret messages
encoded/decoded using clock arithmetic.
- [Coming soon] A decoder for secret messages.
Activities
-
Number bracelets: a game/activity that is based on clock
arithemtic.
- Lots of secret encoded messages
that you can have fun decoding using clock arithmetic.
- [Coming soon] Star polygons: cool pictures to draw
using clock arithemtic.
- [Coming soon] Multiplication line designs:
even cooler pictures to draw using clock arithemtic.
Other people's web pages on clock arithmetic and secret codes
Comments welcome:
susan@math.csusb.edu
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