Working systematically

Tim had nine cards each with a different number from 1 to 9 on it. How could he have put them into three piles so that the total in each pile was 15?

Use the interactivity to find all the different right-angled triangles you can make by just moving one corner of the starting triangle.

Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?

Find the product of the numbers on the routes from A to B. Which route has the smallest product? Which the largest?

A group of children are using measuring cylinders but they lose the labels. Can you help relabel them?

Each light in this interactivity turns on according to a rule. What happens when you enter different numbers? Can you work out the rule for each light?

Find out about the lottery that is played in a far-away land. What is the chance of winning?

How many ways can you find to do up all four buttons on my coat? How about if I had five buttons? Six ...?