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An investigation involving adding and subtracting sets of consecutive numbers. Lots to find out, lots to explore.

Tea Cups

Place the 16 different combinations of cup/saucer in this 4 by 4 arrangement so that no row or column contains more than one cup or saucer of the same colour.

Counting on Letters

The letters of the word ABACUS have been arranged in the shape of a triangle. How many different ways can you find to read the word ABACUS from this triangular pattern?

The Best Card Trick?

Age 11 to 16 Challenge Level:

Here are a few examples:

If we are dealt 3S, 5S, 3D, 4C, 9H:

Place 3S down first (to indicate that the secret card is a spade),
then 3D, 9H, 4C (low, high, middle)
to indicate that the secret card is 2 more than the 3S, i.e. the 5S.


If we are dealt 3S, 9S, 3D, 4C, 9H:

Place 3S down first (to indicate that the secret card is a spade),
then 9H, 4C, 3D (high, middle, low)
to indicate that the secret card is 6 more than the 3S, i.e. the 9S.


If we are dealt 3S, 10S, 3D, 4C, 9H:

Place 10S down first (to indicate that the secret card is a spade),
then 9H, 4C, 3D (high, middle, low)
to indicate that the secret card is 6 more than the 10S, i.e. the 3S.


If we are dealt 2H, JH, 4D, 4C, 4S:

Place JH down first (to indicate that the secret card is a heart),
then 4D, 4S, 4C (middle, high, low)
to indicate that the secret card is 4 more than the JH, i.e.the 2H.