A student in a maths class was trying to get some information from her teacher. She was given some clues and then the teacher ended by saying, "Well, how old are they?"
Given the products of adjacent cells, can you complete this Sudoku?
Can you see how these factor-multiple chains work? Find the chain which contains the smallest possible numbers. How about the largest possible numbers?
Does this 'trick' for calculating multiples of 11 always work? Why or why not?
Can you make square numbers by adding two prime numbers together?
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?
56 406 is the product of two consecutive numbers. What are these two numbers?
Can you work out what a ziffle is on the planet Zargon?
Ben passed a third of his counters to Jack, Jack passed a quarter of his counters to Emma and Emma passed a fifth of her counters to Ben. After this they all had the same number of counters.
In this problem we are looking at sets of parallel sticks that cross each other. What is the least number of crossings you can make? And the greatest?
Is it possible to draw a 5-pointed star without taking your pencil off the paper? Is it possible to draw a 6-pointed star in the same way without taking your pen off?
One quarter of these coins are heads but when I turn over two coins, one third are heads. How many coins are there?
If you have only four weights, where could you place them in order to balance this equaliser?
Can you find different ways of creating paths using these paving slabs?
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?
What is the lowest number which always leaves a remainder of 1 when divided by each of the numbers from 2 to 10?
Can you complete this jigsaw of the multiplication square?
48 is called an abundant number because it is less than the sum of its factors (without itself). Can you find some more abundant numbers?
Your vessel, the Starship Diophantus, has become damaged in deep space. Can you use your knowledge of times tables and some lightning reflexes to survive?
Investigate the sum of the numbers on the top and bottom faces of a line of three dice. What do you notice?
Work out Tom's number from the answers he gives his friend. He will only answer 'yes' or 'no'.
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?
Nine squares with side lengths 1, 4, 7, 8, 9, 10, 14, 15, and 18 cm can be fitted together to form a rectangle. What are the dimensions of the rectangle?
Play the divisibility game to create numbers in which the first two digits make a number divisible by 2, the first three digits make a number divisible by 3...
I throw three dice and get 5, 3 and 2. Add the scores on the three dice. What do you get? Now multiply the scores. What do you notice?
Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.
The discs for this game are kept in a flat square box with a square hole for each. Use the information to find out how many discs of each colour there are in the box.
Suppose we allow ourselves to use three numbers less than 10 and multiply them together. How many different products can you find? How do you know you've got them all?
Investigate the smallest number of moves it takes to turn these mats upside-down if you can only turn exactly three at a time.
How can you use just one weighing to find out which box contains the lighter ten coins out of the ten boxes?
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
I am thinking of three sets of numbers less than 101. They are the red set, the green set and the blue set. Can you find all the numbers in the sets from these clues?
Gabriel multiplied together some numbers and then erased them. Can you figure out where each number was?
Four of these clues are needed to find the chosen number on this grid and four are true but do nothing to help in finding the number. Can you sort out the clues and find the number?
Factor track is not a race but a game of skill. The idea is to go round the track in as few moves as possible, keeping to the rules.
"Ip dip sky blue! Who's 'it'? It's you!" Where would you position yourself so that you are 'it' if there are two players? Three players ...?
When Charlie asked his grandmother how old she is, he didn't get a straightforward reply! Can you work out how old she is?
Becky created a number plumber which multiplies by 5 and subtracts 4. What do you notice about the numbers that it produces? Can you explain your findings?
I am thinking of three sets of numbers less than 101. Can you find all the numbers in each set from these clues?
Nearly all of us have made table patterns on hundred squares, that is 10 by 10 grids. This problem looks at the patterns on differently sized square grids.
Imagine a wheel with different markings painted on it at regular intervals. Can you predict the colour of the 18th mark? The 100th mark?
In this activity, the computer chooses a times table and shifts it. Can you work out the table and the shift each time?
Use the interactivities to complete these Venn diagrams.
Number problems at primary level to work on with others.
Number problems at primary level that may require resilience.
The clues for this Sudoku are the product of the numbers in adjacent squares.
This article for teachers describes how number arrays can be a useful representation for many number concepts.
The planet of Vuvv has seven moons. Can you work out how long it is between each super-eclipse?
A game for 2 people using a pack of cards Turn over 2 cards and try to make an odd number or a multiple of 3.
Can you fill in this table square? The numbers 2 -12 were used to generate it with just one number used twice.