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. . . .
There are two forms of counting on Vuvv - Zios count in base 3 and Zepts count in base 7. One day four of these creatures, two Zios and two Zepts, sat on the summit of a hill to count the legs of. . . .
The number 3723(in base 10) is written as 123 in another base. What is that base?
Consider all of the five digit numbers which we can form using only the digits 2, 4, 6 and 8. If these numbers are arranged in ascending order, what is the 512th number?
When asked how old she was, the teacher replied: My age in years is not prime but odd and when reversed and added to my age you have a perfect square...
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?
Four strategy dice games to consolidate pupils' understanding of rounding.
This is a game in which your counters move in a spiral round the snail's shell. It is about understanding tens and units.
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?
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?
How many positive integers less than or equal to 4000 can be written down without using the digits 7, 8 or 9?
Take the numbers 1, 2, 3, 4 and 5 and imagine them written down in every possible order to give 5 digit numbers. Find the sum of the resulting numbers.
32 x 38 = 30 x 40 + 2 x 8; 34 x 36 = 30 x 40 + 4 x 6; 56 x 54 = 50 x 60 + 6 x 4; 73 x 77 = 70 x 80 + 3 x 7 Verify and generalise if possible.
Number problems for inquiring primary learners.
There are six numbers written in five different scripts. Can you sort out which is which?
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
Replace each letter with a digit to make this addition correct.
A school song book contains 700 songs. The numbers of the songs are displayed by combining special small single-digit boards. What is the minimum number of small boards that is needed?
Each child in Class 3 took four numbers out of the bag. Who had made the highest even number?
You have two sets of the digits 0 – 9. Can you arrange these in the five boxes to make four-digit numbers as close to the target numbers as possible?
Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.
Three people chose this as a favourite problem. It is the sort of problem that needs thinking time - but once the connection is made it gives access to many similar ideas.
What is the sum of all the digits in all the integers from one to one million?
How many six digit numbers are there which DO NOT contain a 5?
Follow the clues to find the mystery number.
Can you replace the letters with numbers? Is there only one solution in each case?
Carry out cyclic permutations of nine digit numbers containing the digits from 1 to 9 (until you get back to the first number). Prove that whatever number you choose, they will add to the same total.
The letters in the following addition sum represent the digits 1 ... 9. If A=3 and D=2, what number is represented by "CAYLEY"?
Think of any three-digit number. Repeat the digits. The 6-digit number that you end up with is divisible by 91. Is this a coincidence?
Who said that adding couldn't be fun?
Can you work out some different ways to balance this equation?
Exploring the structure of a number square: how quickly can you put the number tiles in the right place on the grid?
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Explore the relationship between simple linear functions and their graphs.
Can you complete this calculation by filling in the missing numbers? In how many different ways can you do it?
Number problems at primary level to work on with others.
This activity involves rounding four-digit numbers to the nearest thousand.
Find out what a Deca Tree is and then work out how many leaves there will be after the woodcutter has cut off a trunk, a branch, a twig and a leaf.
Number problems at primary level that may require determination.
Number problems at primary level that require careful consideration.
Nowadays the calculator is very familiar to many of us. What did people do to save time working out more difficult problems before the calculator existed?
What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?
When the number x 1 x x x is multiplied by 417 this gives the answer 9 x x x 0 5 7. Find the missing digits, each of which is represented by an "x" .
This article, written for teachers, looks at the different kinds of recordings encountered in Primary Mathematics lessons and the importance of not jumping to conclusions!
Find the values of the nine letters in the sum: FOOT + BALL = GAME
This multiplication uses each of the digits 0 - 9 once and once only. Using the information given, can you replace the stars in the calculation with figures?
Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?
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.
Consider all two digit numbers (10, 11, . . . ,99). In writing down all these numbers, which digits occur least often, and which occur most often ? What about three digit numbers, four digit numbers. . . .
The number 27 is special because it is three times the sum of its digits 27 = 3 (2 + 7). Find some two digit numbers that are SEVEN times the sum of their digits (seven-up numbers)?