Odd and even numbers

problem
Prime magic

Age

7 to 16

Challenge level

Place the numbers 1, 2, 3,..., 9 one on each square of a 3 by 3 grid so that all the rows and columns add up to a prime number. How many different solutions can you find?
problem
Jenny's logic

Age

11 to 14

Challenge level

Weekly Problem 52 - 2009
How did Jenny figure out that Tom's cards added to an even number?
problem
Next-door numbers

Age

5 to 7

Challenge level

Florence, Ethan and Alma have each added together two 'next-door' numbers. What is the same about their answers?
problem
Eightness of eight

Age

5 to 7

Challenge level

What do you see as you watch this video? Can you create a similar video for the number 12?
problem
Share bears

Age

5 to 7

Challenge level

Yasmin and Zach have some bears to share. Which numbers of bears can they share so that there are none left over?
problem
The set of numbers

Age

5 to 7

Challenge level

Can you place the numbers from 1 to 10 in the grid?
problem
Domino sorting

Age

5 to 7

Challenge level

Try grouping the dominoes in the ways described. Are there any left over each time? Can you explain why?
problem
Sorting numbers

Age

5 to 7

Challenge level

Can you sort numbers into sets? Can you give each set a name?
problem
Lots of biscuits!

Age

5 to 7

Challenge level

Help share out the biscuits the children have made.
problem
Even and odd

Age

5 to 7

Challenge level

This activity is best done with a whole class or in a large group. Can you match the cards? What happens when you add pairs of the numbers together?