Four by four
Take four different shapes in each of four different colours.
Arrange them in a four-by-four array so that no two shapes of the same kind and no two colours of the same kind appear in the same row or column.
SOLUTIONS Four by four (ages 6 to 11) Other solutions are possible
Squares and cubes
Solve the mysteries.
* I am a two-digit square number. I am 17 more than the previous square number. Who am I?
* I am a two-digit multiple of eleven. The product of my two digits is a cube and a square. Who am I?
* I am a two-digit cube number. When you exchange my digits the number formed is the product of a cube and a square. Who am I?
* I am a three-digit cube number. When you rearrange my digits you get a smaller cube number. Who am I?
* I am a three-digit number that is also square. Who am I?
SOLUTION Squares and cubes (ages 10 to 14) 81; 88; 27; 512; 729