Working systematically

What is the greatest number of counters you can place on the grid below without four of them lying at the corners of a square?

Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.

The items in the shopping basket add and multiply to give the same amount. What could their prices be?

Can you work out the arrangement of the digits in the square so that the given products are correct? The numbers 1 - 9 may be used once and once only.

Choose four different digits from 1-9 and put one in each box so that the resulting four two-digit numbers add to a total of 100.

Mrs Morgan, the class's teacher, pinned numbers onto the backs of three children. Use the information to find out what the three numbers were.

Ram divided 15 pennies among four small bags. He could then pay any sum of money from 1p to 15p without opening any bag. How many pennies did Ram put in each bag?

The discs for this game are kept in a flat square box with a square hole for each. Use the information to find out how many discs of each colour there are in the box.

Find your way through the grid starting at 2 and following these operations. What number do you end on?