Stage: 1 Challenge Level: 
This challenge is best done in a group of at least four children.
You'll need to print out this sheet and cut it into separate cards.
Share all the cards out amongst the group.
Can you each work out the number on your card?
What do you notice? How could you sort or arrange the cards?
Comparing and Ordering numbers. Counting. Interactivities. Combinations. Working systematically. Investigations. Trial and improvement. Properties of numbers. Addition & subtraction. Multiplication & division.
Published February 2010.
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email: nrich@damtp.cam.ac.uk