Problem Pictures
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PP1 CD-ROM cover

This picture is taken from the Problem Pictures CD-ROM of photographs with activities for mathematics teaching.

Hair dryer

The picture shows the ventilation holes in a hair dryer.

There are 9 holes in the first circle and 12 holes in the next circle. How does the pattern continue?

Try to figure out an answer before counting the holes in the picture.

Figure out the total number of holes without counting them.


The photographs and screen images on this website are copyright and may not be reproduced without permission. Copyright Richard Phillips 2001/2008. Page updated 27 November 2008.