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Our school dinners offer the same basic choice each day.
Starter: soup or salad;
Main course: pasta, fishcakes, pizza, burger or curry;
Dessert: crumble, cake or fruit salad
I change my choice for each course every day, trying each option in turn, going back to soup after salad, to pasta after curry and to crumble after fruit salad.
Today, I shall sit down to soup, pasta and crumble.
How many school dinners will I have eaten before I next sit down to the same combination again?
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.