problem Possible Pieces Age 5 to 11 Challenge level Can you create jigsaw pieces which are based on a square shape, with at least one peg and one hole?
problem Gabriel's Problem Age 11 to 14 Challenge level Gabriel multiplied together some numbers and then erased them. Can you figure out where each number was?
problem Multiplication Table Puzzle Age 11 to 14 Challenge level In the multiplication table on the right, only some of the numbers have been given. What is the value of A+B+C+D+E?
problem Half and Half Age 11 to 14 Challenge level Two of the four small triangles are to be painted black. In how many ways can this be done?
problem Threes and Fours Age 14 to 16 Challenge level What is the smallest integer where every digit is a 3 or a 4 and it is divisible by both 3 and 4?
problem Isometric Rhombuses Age 11 to 14 Challenge level Weekly Problem 31 - 2016 The diagram shows a grid of $16$ identical equilateral triangles. How many rhombuses are there made up of two adjacent small triangles?
problem End of a Prime Age 14 to 16 Challenge level I made a list of every number that is the units digit of at least one prime number. How many digits appear in the list?
problem Middle Digit Mean Age 11 to 16 Challenge level Weekly Problem 16 - 2016 How many three digit numbers have the property that the middle digit is the mean of the other two digits?
problem Growing Surprises Age 11 to 14 Challenge level Can you find the connections between linear and quadratic patterns?
problem Making a difference Age 11 to 14 Challenge level How many different differences can you make?