# Clickety Click and All the Sixes

##### Age 16 to 18

Challenge Level

### Why do this
problem?

A non-standard problem based on place value and summing geometric
series requiring simple manipulation of a numerical
expression.

### Possible approach

A short problem suitable as a lesson starter.

### Key questions

Can you write the 10 digit number $6666666666$ as a geometric
series?

Can you sum this series?

Can you do the same for any number that is a 'string of
sixes'?

### Possible extension

For a discussion of a generalisation of this problem see

Sum The Series.