Number problems at primary level to work on with others.
Number problems at primary level that may require resilience.
What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?
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?
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
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?
Can you replace the letters with numbers? Is there only one solution in each case?
What is the sum of all the digits in all the integers from one to one million?
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?
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?
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?
Can you substitute numbers for the letters in these sums?
Find the sum of all three-digit numbers each of whose digits is odd.
There are six numbers written in five different scripts. Can you sort out which is which?
In the multiplication calculation, some of the digits have been replaced by letters and others by asterisks. Can you reconstruct the original multiplication?
Follow the clues to find the mystery number.
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 complete this calculation by filling in the missing numbers? In how many different ways can you do it?
Have a go at balancing this equation. Can you find different ways of doing it?
Can you work out some different ways to balance this equation?
Number problems at primary level that require careful consideration.
Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.
This 100 square jigsaw is written in code. It starts with 1 and ends with 100. Can you build it up?
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?
Each child in Class 3 took four numbers out of the bag. Who had made the highest even number?
Number problems for inquiring primary learners.
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?
Amazing as it may seem the three fives remaining in the following `skeleton' are sufficient to reconstruct the entire long division sum.
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" .
Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?
Who said that adding couldn't be fun?
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.
What happens when you round these numbers to the nearest whole number?
Find the values of the nine letters in the sum: FOOT + BALL = GAME
Use two dice to generate two numbers with one decimal place. What happens when you round these numbers to the nearest whole number?
Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.
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.
What happens when you round these three-digit numbers to the nearest 100?
Explore the relationship between simple linear functions and their graphs.
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?
The number 3723(in base 10) is written as 123 in another base. What is that base?
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.
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.
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. . . .
How many six digit numbers are there which DO NOT contain a 5?
How many positive integers less than or equal to 4000 can be written down without using the digits 7, 8 or 9?
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?
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Replace each letter with a digit to make this addition correct.