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Find all the triples of numbers a, b, c such that each one of them plus the product of the other two is always 2.
Not Continued Fractions
Which rational numbers cannot be written in the form x + 1/(y + 1/z) where x, y and z are integers?
Coffee
To make 11 kilograms of this blend of coffee costs £15 per kilogram. The blend uses more Brazilian, Kenyan and Mocha coffee... How many kilograms of each type of coffee are used?
Age 14 to 16 Short Challenge Level:
There are 20 black socks and $n$ white socks in a drawer.
A sock is taken from the drawer, and the probability that it is white is $\dfrac{1}{n}$.
What is the value of $n$?
This problem is adapted from the World Mathematics Championships
You can find more short problems, arranged by curriculum topic, in our short problems collection.
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NRICH is part of the family of activities in the Millennium Mathematics Project.
NRICH is part of the family of activities in the Millennium Mathematics Project.