Image
You can build on these ideas when exploring our Public Key Cryptography Interactivity, and see how Public Keys are used to keep our personal information secure.
You can watch a recording of the webinar in which we discussed the mathematical thinking which can be prompted by these problems.
The last day for sending in solutions to our live problems is Monday 17 May.
problem
Clock arithmetic
Age
11 to 18
Challenge level
What happens if we change the rules and make the usual straight number line into a circle?
problem
More adventures with modular arithmetic
Age
14 to 18
Challenge level
Investigate what happens when we add or multiply numbers using modular arithmetic.
problem
Clock squares
Age
14 to 18
Challenge level
Can you find a way of predicting the value of large square numbers with the help of our power modulo calculator?
problem
Euler's totient function
Age
16 to 18
Challenge level
How many numbers are there less than $n$ which have no common factors with $n$?
article
Public key cryptography
An introduction to coding and decoding messages and the maths behind how to secretly share information.
interactivity
Public key cryptography interactivity
Here's a chance to simulate sending secret messages and trying to decode them.
article
An introduction to number theory
An introduction to some beautiful results in Number Theory.
We are very grateful to the Heilbronn Institute for Mathematical Research for their generous support for the development of these resources.