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problem
Tetra slice
16 to 18
Can you prove that a quadrilateral drawn inside a tetrahedron is a parallelogram?
problem
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Finding fifteen
7 to 11
Tim had nine cards each with a different number from 1 to 9 on it. How could he have put them into three piles so that the total in each pile was 15?
article
The development of algebra - 1
This is the first of a two part series of articles on the history
of Algebra from about 2000 BCE to about 1000 CE.
problem
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Tilted squares
11 to 14
It's easy to work out the areas of most squares that we meet, but what if they were tilted?
article
Meet the Nim family
Jennifer Piggott and the NRICH team introduce Nim-like games to help children think creatively in mathematics.
problem
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How old am I?
14 to 16
In 15 years' time my age will be the square of my age 15 years ago. Can you work out my age, and when I had other special birthdays?
problem
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Frogs
11 to 14
How many moves does it take to swap over some red and blue frogs? Do you have a method?
problem
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Attractive tablecloths
14 to 16
Charlie likes tablecloths that use as many colours as possible, but insists that his tablecloths have some symmetry. Can you work out how many colours he needs for different tablecloth designs?
problem
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School fair necklaces
5 to 11
How many possible symmetrical necklaces can you find? How do you know you've found them all?