What is the sum of all the digits in all the integers from one to one million?
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?
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?
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. . . .
Investigate the different ways these aliens count in this challenge. You could start by thinking about how each of them would write our number 7.
Replace each letter with a digit to make this addition correct.
Using balancing scales what is the least number of weights needed to weigh all integer masses from 1 to 1000? Placing some of the weights in the same pan as the object how many are needed?
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?
This is a game in which your counters move in a spiral round the snail's shell. It is about understanding tens and units.
This activity involves rounding four-digit numbers to the nearest thousand.
Four strategy dice games to consolidate pupils' understanding of rounding.
Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.
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?
Who said that adding couldn't be fun?
Number problems for inquiring primary learners.
The number 3723(in base 10) is written as 123 in another base. What is that base?
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?
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.
Number problems at primary level that may require resilience.
Number problems at primary level that require careful consideration.
Number problems at primary level to work on with others.
Choose any 3 digits and make a 6 digit number by repeating the 3 digits in the same order (e.g. 594594). Explain why whatever digits you choose the number will always be divisible by 7, 11 and 13.
Take any four digit number. Move the first digit to the 'back of the queue' and move the rest along. Now add your two numbers. What properties do your answers always have?
How many positive integers less than or equal to 4000 can be written down without using the digits 7, 8 or 9?
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?
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?
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?
What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?
Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?
Follow the clues to find the mystery number.
What happens when you round these three-digit numbers to the nearest 100?
Use two dice to generate two numbers with one decimal place. What happens when you round these numbers to the nearest whole number?
Have a go at balancing this equation. Can you find different ways of doing it?
Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.
How many six digit numbers are there which DO NOT contain a 5?
Can you complete this calculation by filling in the missing numbers? In how many different ways can you do it?
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?
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Exploring the structure of a number square: how quickly can you put the number tiles in the right place on the grid?
Can you work out some different ways to balance this equation?
Can you replace the letters with numbers? Is there only one solution in each case?
Each child in Class 3 took four numbers out of the bag. Who had made the highest even number?
Pick the number of times a week that you eat chocolate. This number must be more than one but less than ten. Multiply this number by 2. Add 5 (for Sunday). Multiply by 50... Can you explain why it. . . .
Can you show that 1^99 + 2^99 + 3^99 + 4^99 + 5^99 is divisible by 5?
This article for the young and old talks about the origins of our number system and the important role zero has to play in it.
A church hymn book contains 700 hymns. The numbers of the hymns are displayed by combining special small single-digit boards. What is the minimum number of small boards that is needed?
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?
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.