Here is a chance to play a fractions version of the classic Countdown Game.
When I type a sequence of letters my calculator gives the product of all the numbers in the corresponding memories. What numbers should I store so that when I type 'ONE' it returns 1, and when I type. . . .
What happens when you add a three digit number to its reverse?
Charlie has made a Magic V. Can you use his example to make some more? And how about Magic Ls, Ns and Ws?
There are nasty versions of this dice game but we'll start with the nice ones...
Using some or all of the operations of addition, subtraction, multiplication and division and using the digits 3, 3, 8 and 8 each once and only once make an expression equal to 24.
Try entering different sets of numbers in the number pyramids. How does the total at the top change?
Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.
Can you explain the strategy for winning this game with any target?
What is the largest number you can make using the three digits 2, 3 and 4 in any way you like, using any operations you like? You can only use each digit once.
In this 100 square, look at the green square which contains the numbers 2, 3, 12 and 13. What is the sum of the numbers that are diagonally opposite each other? What do you notice?
How many solutions can you find to this sum? Each of the different letters stands for a different number.
This article explains how to make your own magic square to mark a special occasion with the special date of your choice on the top line.
Replace each letter with a digit to make this addition correct.
If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?
This is an adding game for two players. Can you be the first to reach the target?
The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?
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. . . .
Here is a chance to play a version of the classic Countdown Game.
Annie cut this numbered cake into 3 pieces with 3 cuts so that the numbers on each piece added to the same total. Where were the cuts and what fraction of the whole cake was each piece?
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?
Find out why these matrices are magic. Can you work out how they were made? Can you make your own Magic Matrix?
In the following sum the letters A, B, C, D, E and F stand for six distinct digits. Find all the ways of replacing the letters with digits so that the arithmetic is correct.
This addition sum uses all ten digits 0, 1, 2...9 exactly once. Find the sum and show that the one you give is the only possibility.
Place this "worm" on the 100 square and find the total of the four squares it covers. Keeping its head in the same place, what other totals can you make?
15 = 7 + 8 and 10 = 1 + 2 + 3 + 4. Can you say which numbers can be expressed as the sum of two or more consecutive integers?
We start with one yellow cube and build around it to make a 3x3x3 cube with red cubes. Then we build around that red cube with blue cubes and so on. How many cubes of each colour have we used?
This article gives you a few ideas for understanding the Got It! game and how you might find a winning strategy.
Can you draw a continuous line through 16 numbers on this grid so that the total of the numbers you pass through is as high as possible?
Number problems at primary level that require careful consideration.
Crosses can be drawn on number grids of various sizes. What do you notice when you add opposite ends?
Complete these two jigsaws then put one on top of the other. What happens when you add the 'touching' numbers? What happens when you change the position of the jigsaws?
Do you notice anything about the solutions when you add and/or subtract consecutive negative numbers?
Delight your friends with this cunning trick! Can you explain how it works?
By selecting digits for an addition grid, what targets can you make?
Got It game for an adult and child. How can you play so that you know you will always win?
Investigate the different ways that fifteen schools could have given money in a charity fundraiser.
This article for primary teachers encourages exploration of two fundamental ideas, exchange and 'unitising', which will help children become more fluent when calculating.
Choose two digits and arrange them to make two double-digit numbers. Now add your double-digit numbers. Now add your single digit numbers. Divide your double-digit answer by your single-digit answer. . . .
The Scot, John Napier, invented these strips about 400 years ago to help calculate multiplication and division. Can you work out how to use Napier's bones to find the answer to these multiplications?
Can you explain how this card trick works?
Try out some calculations. Are you surprised by the results?
Can you find different ways of creating paths using these paving slabs?
Strike it Out game for an adult and child. Can you stop your partner from being able to go?
Investigate what happens when you add house numbers along a street in different ways.
Find the values of the nine letters in the sum: FOOT + BALL = GAME
A combination mechanism for a safe comprises thirty-two tumblers numbered from one to thirty-two in such a way that the numbers in each wheel total 132... Could you open the safe?
Is it possible to rearrange the numbers 1,2......12 around a clock face in such a way that every two numbers in adjacent positions differ by any of 3, 4 or 5 hours?
In this simulation of a balance, you can drag numbers and parts of number sentences on to the trays. Have a play!
Can you arrange the digits 1,2,3,4,5,6,7,8,9 into three 3-digit numbers such that their total is close to 1500?