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Calendar Capers

Choose any three by three square of dates on a calendar page...

Adding All Nine

Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself!


Draw a 'doodle' - a closed intersecting curve drawn without taking pencil from paper. What can you prove about the intersections?

The Bridges of Konigsberg

Age 11 to 18
Challenge Level

Euler used a graph to explain the possible routes around Old Konisberg. He represented the land by dots and the bridges by lines joining the dots. Think about whether there is an even number of bridges or an odd number of bridges from each piece of land. diagram showing nodes and lines