Pebbles

Place four pebbles on the sand in the form of a square. Keep adding as few pebbles as necessary to double the area. How many extra pebbles are added each time?

Adding All Nine

Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some other possibilities for yourself!

GOT IT Now

For this challenge, you'll need to play Got It! Can you explain the strategy for winning this game with any target?

Factors and Multiples Puzzle

Stage: 3 Challenge Level:

Can a number be both odd and even?
What does this tell you about where the ODD NUMBER and EVEN NUMBER headings have to go?
Can you use this idea to position any of the other heading cards?

If you have reached a stage where you have placed most of the numbers but have a few that you cannot place, don't panic!
Could you swap one of the numbers that you can't place for a number that is already on the grid?
You might be able to swap them and then find that the number you have removed can be placed on one of the empty squares.

Don't forget: $1$ is not a prime number!

Triangle numbers can be represented by a triangular array of squares
The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice. More information on many of our other activities can be found here.
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