Four bags contain a large number of 1s, 3s, 5s and 7s. Pick any ten numbers from the bags above so that their total is 37.

A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.

The idea of this game is to add or subtract the two numbers on the dice and cover the result on the grid, trying to get a line of three. Are there some numbers that are good to aim for?

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

How many solutions can you find to this sum? Each of the different letters stands for a different number.

Can you see why 2 by 2 could be 5? Can you predict what 2 by 10 will be?

Here is a chance to play a version of the classic Countdown Game.

Can you use the numbers on the dice to reach your end of the number line before your partner beats you?

Place the numbers from 1 to 9 in the squares below so that the difference between joined squares is odd. How many different ways can you do this?

This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.

In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?

If you have only four weights, where could you place them in order to balance this equaliser?

Place six toy ladybirds into the box so that there are two ladybirds in every column and every row.

Find out about Magic Squares in this article written for students. Why are they magic?!

Make your own double-sided magic square. But can you complete both sides once you've made the pieces?

Can you put the numbers 1 to 8 into the circles so that the four calculations are correct?

Place the numbers 1 to 6 in the circles so that each number is the difference between the two numbers just below it.

Use the information about Sally and her brother to find out how many children there are in the Brown family.

Use your logical reasoning to work out how many cows and how many sheep there are in each field.

How have the numbers been placed in this Carroll diagram? Which labels would you put on each row and column?

Can you hang weights in the right place to make the equaliser balance?

Using 3 rods of integer lengths, none longer than 10 units and not using any rod more than once, you can measure all the lengths in whole units from 1 to 10 units. How many ways can you do this?

Find at least one way to put in some operation signs (+ - x ÷) to make these digits come to 100.

In how many ways could Mrs Beeswax put ten coins into her three puddings so that each pudding ended up with at least two coins?

Use the number weights to find different ways of balancing the equaliser.

This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?

Can you make a cycle of pairs that add to make a square number using all the numbers in the box below, once and once only?

Put the numbers 1, 2, 3, 4, 5, 6 into the squares so that the numbers on each circle add up to the same amount. Can you find the rule for giving another set of six numbers?

Use the interactivities to fill in these Carroll diagrams. How do you know where to place the numbers?

Start by putting one million (1 000 000) into the display of your calculator. Can you reduce this to 7 using just the 7 key and add, subtract, multiply, divide and equals as many times as you like?

Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?

Choose four of the numbers from 1 to 9 to put in the squares so that the differences between joined squares are odd.

In this game, you can add, subtract, multiply or divide the numbers on the dice. Which will you do so that you get to the end of the number line first?

Exactly 195 digits have been used to number the pages in a book. How many pages does the book have?

Place the numbers 1 to 10 in the circles so that each number is the difference between the two numbers just below it.

Sweets are given out to party-goers in a particular way. Investigate the total number of sweets received by people sitting in different positions.

If each of these three shapes has a value, can you find the totals of the combinations? Perhaps you can use the shapes to make the given totals?

This challenge is about finding the difference between numbers which have the same tens digit.

Starting with the number 180, take away 9 again and again, joining up the dots as you go. Watch out - don't join all the dots!

Two children made up a game as they walked along the garden paths. Can you find out their scores? Can you find some paths of your own?

This challenge extends the Plants investigation so now four or more children are involved.

In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.

If you hang two weights on one side of this balance, in how many different ways can you hang three weights on the other side for it to be balanced?

This challenging activity involves finding different ways to distribute fifteen items among four sets, when the sets must include three, four, five and six items.

This challenge focuses on finding the sum and difference of pairs of two-digit numbers.

Make one big triangle so the numbers that touch on the small triangles add to 10. You could use the interactivity to help you.