Working systematically

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.

This challenging activity involves finding different ways to distribute fifteen items among four sets, when the sets must include three, four, five and six items.

A challenging activity focusing on finding all possible ways of stacking rods.

Can you put the 25 coloured tiles into the 5 × 5 square so that no column, no row and no diagonal line have tiles of the same colour in them?

Can you find numbers between 100 and 999 that have a middle digit equal to the sum of the other two digits?

Countries from across the world competed in a sports tournament. Can you devise an efficient strategy to work out the order in which they finished?

The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?

In a league of 5 football teams which play in a round robin tournament show that it is possible for all five teams to be league leaders.

How many routes are there in this diagram from S to T?