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Challenge level: Challenge Level:1 Challenge Level:2 Challenge Level:3

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Broad Topics > Calculations and Numerical Methods > Inverses

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Journeys in Numberland

Stage: 2 Challenge Level: Challenge Level:1

Tom and Ben visited Numberland. Use the maps to work out the number of points each of their routes scores.

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The Add and Take-away Path

Stage: 1 Challenge Level: Challenge Level:1

Two children made up a game as they walked along the garden paths. Can you find out their scores? Can you find some paths of your own?

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Which Symbol?

Stage: 2 Challenge Level: Challenge Level:1

Choose a symbol to put into the number sentence.

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Alphabetti Sudoku

Stage: 3 and 4 Challenge Level: Challenge Level:1

This Sudoku requires you to do some working backwards before working forwards.

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The Mean Problem

Stage: 4 Challenge Level: Challenge Level:1

There are four unknown numbers. The mean of the first two numbers is 4, and the mean of the first three numbers is 9. The mean of all four numbers is 15. If one of the four numbers was 2, what were. . . .

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Groups of Sets

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

The binary operation * for combining sets is defined as the union of two sets minus their intersection. Prove the set of all subsets of a set S together with the binary operation * forms a group.

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What's a Group?

Stage: 5 Challenge Level: Challenge Level:2 Challenge Level:2

Explore the properties of some groups such as: The set of all real numbers excluding -1 together with the operation x*y = xy + x + y. Find the identity and the inverse of the element x.