Brain Teaser: Get in Gear

The number on each gear is the number of teeth it has. If you turn any one of the gears, the others also turn. The middle gear turns in the opposite direction of the other two gears.

The gears are now in their starting position. If you start turning them and continue to turn them, eventually all three will end up at their starting positions.

How many complete turns will each gear make in order to have all three back in their starting positions?

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For a better understanding of gears, play with the two gear exhibits in the Discovery Centre and have a look at the open gear box.

If you want to know more about gears go to:
How Gear Ratios Work

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