Working systematically
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problemLeftovers
Weekly Problem 26 - 2008
If $n$ is a positive integer, how many different values for the remainder are obtained when $n^2$ is divided by $n+4$? -
problemThe Great Weights Puzzle
You have twelve weights, one of which is different from the rest. Using just 3 weighings, can you identify which weight is the odd one out, and whether it is heavier or lighter than the rest?
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problemFactor List
Tina has chosen a number and has noticed something about its factors. What number could she have chosen? Are there multiple possibilities?
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problemPhone Call
How many different phone numbers are there starting with a 3 and with at most two different digits?
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problemSymmetricality
Five equations and five unknowns. Is there an easy way to find the unknown values?
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problemFlipping Twisty Matrices
Investigate the transformations of the plane given by the 2 by 2 matrices with entries taking all combinations of values 0, -1 and +1.
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problemTwin Chute-Swapping Sudoku
A pair of Sudokus with lots in common. In fact they are the same problem but rearranged. Can you find how they relate to solve them both?
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problemDifference Dynamics
Take three whole numbers. The differences between them give you three new numbers. Find the differences between the new numbers and keep repeating this. What happens?