Stage: 4 Challenge Level: 
The coke machine in college takes 50 pence pieces. It also takes a certain foreign coin of traditional design.
Coins inserted into the machine slide down a chute into the machine and a drink is duly released.
How many more revolutions does the foreign coin make over the 50 pence piece going down the chute?
Complex numbers. Perimeters. Reflections. Mathematical reasoning & proof. Right angled triangles. Interactivities. Mixed trig ratios. Symmetry. Visualising. Rotations.
Published May 1999.
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