Live Problems - Stage 4 & 5

Each time you visit the NRICH site there will be some activities which are 'live'. That means we are inviting you to send us your solutions and we will publish a selection of them, along with your name and your school's name. If you'd like to know more about what we're looking for, read this short article.

The last day for sending in solutions to our live problems is Monday 17 May.

More Adventures with Modular Arithmeticlive

Age 14 to 18
Challenge Level

Investigate what happens when we add or multiply numbers using modular arithmetic.

Euler's Totient Functionlive

Age 16 to 18
Challenge Level

How many numbers are there less than $n$ which have no common factors with $n$?

Clock Squareslive

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?