Light the Lights
Stage: 1 Challenge Level: 
Investigate which numbers make these lights come on. What is the smallest number you can find that lights up all the lights?
That Number Square!
Stage: 1 and 2 Challenge Level:
How quickly can you put back the numbers on the hundred square? What's the smartest way to do it?
The Deca Tree
Stage: 2 Challenge Level:
Find out what a Deca Tree is and then work out how many leaves there will be after the woodcutter has cut off a trunk, a branch, a twig and a leaf.
The Thousands Game
Stage: 2 Challenge Level:
Each child in Class 3 took four numbers out of the bag. Who had made the highest even number?
What Do You Need?
Stage: 2 Challenge Level:
Four of these clues are needed to find the chosen number on this grid and four are true but do nothing to help in finding the number. Can you sort out the clues and find the number?
Four-digit Targets
Stage: 2 Challenge Level:
You have two sets of the digits 0 – 9. Can you arrange these in the five boxes to make four-digit numbers as close to the target numbers as possible?
Coded Hundred Square
Stage: 2 Challenge Level:
This 100 square jigsaw is written in code. It starts with 1 and ends with 100. Can you build it up?
Which Scripts?
Stage: 2 Challenge Level:
There are six numbers written in five different scripts. Can you sort out which is which?
Which Is Quicker?
Stage: 2 Challenge Level:
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
Nice or Nasty
Stage: 2 and 3 Challenge Level:
There are nasty versions of this dice game but we'll start with the nice ones...
Dicey Operations
Stage: 3 Challenge Level:
Who said that adding, subtracting, multiplying and dividing couldn't be fun?
NRICH is part of the family of activities in the Millennium Mathematics Project.