Odd and even numbers

problem
Arrangements

Age

7 to 11

Challenge level

Is it possible to place 2 counters on the 3 by 3 grid so that there is an even number of counters in every row and every column? How about if you have 3 counters or 4 counters or....?
problem
Sets of four numbers

Age

7 to 11

Challenge level

There are ten children in Becky's group. Can you find a set of numbers for each of them? Are there any other sets?
problem
The set of numbers

Age

5 to 7

Challenge level

Can you place the numbers from 1 to 10 in the grid?
problem
The thousands game

Age

7 to 11

Challenge level

Each child in Class 3 took four numbers out of the bag. Who had made the highest even number?
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
Number tracks

Age

7 to 11

Challenge level

Ben's class were cutting up number tracks. First they cut them into twos and added up the numbers on each piece. What patterns could they see?
problem
Break it up!

Age

5 to 11

Challenge level

In how many different ways can you break up a stick of seven interlocking cubes? Now try with a stick of eight cubes and a stick of six cubes. What do you notice?
problem
Odd squares

Age

7 to 11

Challenge level

Think of a number, square it and subtract your starting number. Is the number you're left with odd or even? How do the images help to explain this?
problem
Picturing square numbers

Age

11 to 14

Challenge level

Square numbers can be represented as the sum of consecutive odd numbers. What is the sum of 1 + 3 + ..... + 149 + 151 + 153?
problem
A mixed-up clock

Age

7 to 11

Challenge level

There is a clock-face where the numbers have become all mixed up. Can you find out where all the numbers have got to from these ten statements?