Problems

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A gang of three jewel thieves has stolen some gold coins and wants to divide them fairly. However, they each have one unusual rule: (i) The first thief wants the number of coins to be divisible by \(3\) so they can split it evenly. (ii) The second thief wants the number of coins to be divisible by \(5\) because she wants to split her share with her four siblings. (iii) The third thief wants the number of coins to be divisible by \(7\) since he wants to split his share amongst seven company stocks.

However, they’re stuck as the number of coins isn’t divisible by any of these numbers. In fact, the number of coins is \(1\) more than a multiple of \(3\), \(3\) more than a multiple of \(5\) and \(5\) more than a multiple of \(7\).
What’s the smallest number of coins they could have? (And if you’re feeling generous, how would you help them out?)

Draw how to tile the whole plane with figures, composed from squares \(1\times 1\), \(2\times 2\), \(3\times 3\), \(4\times 4\), and \(5\times 5\) where squares of all sizes are used the same amount of times in the design of the figure.

Four siblings received magic wands for Christmas. It turned out that any three magic wands can form a triangle in such a way that the areas of all four triangles are equal. Are all the magic wands necessarily the same length?

A goat and a cow would take \(45\) days to eat a full cart of hay. It would take a cow and a sheep \(60\) days, but a sheep and a goat would need \(90\) days. How many days would it take for all three animals to eat all the hay?