Score

There are exactly 3 ways to add 4 odd numbers to get 10. Find all the ways of adding 8 odd numbers to get 20. To be sure of getting all the solutions you will need to be systematic. What about a total of 15 with 6 odd numbers?

Great Granddad is very proud of his telegram from the Queen congratulating him on his hundredth birthday and he has friends who are even older than he is... When was he born?

Prime Magic

Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?

Weekly Problem 12 - 2007

Stage: 3 Short Challenge Level:
Kan must know for sure that Roo's cards are either both even or both odd. The only way he can be sure of this is if he's selected the three even cards leaving Roo only odd numbered cards. Therefore Kan has cards $2$, $4$ and $6$ and the sum of his cards is $12$.

This problem is taken from the UKMT Mathematical Challenges.

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