Copyright © University of Cambridge. All rights reserved.

## 'Beat the Drum Beat!' printed from http://nrich.maths.org/

This problem follows on from

We'll Bang the Drum so you may like to
try that one first if you haven't already.

Here are drums that can be placed on a wheel. As the wheel goes
round, each drum beats.

Before you read any further, explore the interactivity by making
some different rhythms.

In how many ways can you create a rhythm with a steady beat?

Explain how you have done this.

If there were 12 positions on the wheel, in how many ways would you
be able to create a steady beat? How do you know?

Now place just three drums on the wheel to create a new
rhythm.

What would happen if you played this rhythm backwards? Would it
sound different?

Using three drums, make a rhythm which would sound the same
forwards as it does backwards.

How many different ways can you do this using just three
drums?

Now try creating rhythms which sound the same forwards and
backwards with four drums.

How about five drums?

How could you tell just by looking at the arrangement of drums
whether it would sound the same when the wheel rolled forwards or
backwards?

Full Screen Version
This text is usually replaced by the Flash movie.