puzzle

Crooked coin: Solution
Making a biased coin fair.
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Crooked coin
Making a biased coin fair.
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It's a long way to the top: Solution
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It's a long way to the top
In how many ways can you make it up the stairs?
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Five Martin Gardner eye-openers involving squares and cubes

This week would have been the 100th birthday of Martin Gardner, who is deservedly credited with turning on several generations of people worldwide to the pleasures of maths! To mark the occasion here are some favourite puzzles that, apart from being fun, also lead to some serious maths.

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Prime mystery
Making a very special number out of primes.
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An unusual sales pitch
A life insurance agent knocks on a door. A woman answers and he tries to sell her a policy. He asks her how many children she has and their ages. She replies: "I have three children, but I will not even listen to your sales pitch unless you guess their ages..."
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Mystery number
Find the number x that satisfies two interesting properties.
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Mad robot
A mad robot sets off on a journey mindlessly following a set of instructions. Where will it explode?
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Kill the vampire
Sharpen that wooden stake!
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Round peg in square hole or square peg in round hole?
Which gives a tighter fit: a square peg in a round hole or a round peg in a square hole?
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Jail break
How many prisoners escape after visits from wardens?
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