Working systematically

problem
Calendar sorting

Age

7 to 11

Challenge level

The pages of my calendar have got mixed up. Can you sort them out?
problem
Play to 37

Age

7 to 11

Challenge level

In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.
problem
Gridlines

Age

14 to 16

Challenge level

How many triples of points are there in this 4x4 array that lie on a straight line?
problem
Switch on

Age

14 to 16

Challenge level

In how many different ways can a row of five "on/off" switches be set so that no two adjacent switches are in the "off" position?
problem
Latin multiplication

Age

11 to 14

Challenge level

Can you choose one number from each row and column in this grid to form the largest possibe product?
problem
Bugs in the garden

Age

5 to 7

Challenge level

In Sam and Jill's garden there are two sorts of bugs with 7 spots or 4 spots. What numbers of total spots can you make?
problem
Fives on the clock

Age

7 to 11

Challenge level

On a digital clock showing 24-hour time, over a whole day, how many times does a 5 appear?
problem
Subtracting to 2008

Age

11 to 14

Challenge level

Can you work out the sum of the missing digits in this subtraction?
problem
Magic error

Age

11 to 14

Challenge level

Two of the numbers in a 4x4 magic square have been swapped. Can you work out the sum of these numbers?
problem
Phone call

Age

14 to 16

Challenge level

How many different phone numbers are there starting with a 3 and with at most two different digits?