Find the sum of all three-digit numbers each of whose digits is odd.
Number problems at primary level that may require determination.
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?
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 require careful consideration.
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?
Use two dice to generate two numbers with one decimal place. What happens when you round these numbers to the nearest whole number?
Can you substitute numbers for the letters in these sums?
Who said that adding couldn't be fun?
What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?
What happens when you round these three-digit numbers to the nearest 100?
Number problems at primary level to work on with others.
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?
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 replace the letters with numbers? Is there only one solution in each case?
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.
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?
Have a go at balancing this equation. Can you find different ways of doing it?
Can you complete this calculation by filling in the missing numbers? In how many different ways can you do it?
What happens when you round these numbers to the nearest whole number?
Can you work out some different ways to balance this equation?
This 100 square jigsaw is written in code. It starts with 1 and ends with 100. Can you build it up?
Follow the clues to find the mystery number.
In the multiplication calculation, some of the digits have been replaced by letters and others by asterisks. Can you reconstruct the original multiplication?
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?
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?
Number problems for inquiring primary learners.
This activity involves rounding four-digit numbers to the nearest thousand.
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?
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?
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
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?
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?
How many six digit numbers are there which DO NOT contain a 5?
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 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.
How many solutions can you find to this sum? Each of the different letters stands for a different number.
Exploring the structure of a number square: how quickly can you put the number tiles in the right place on the grid?
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?
Replace each letter with a digit to make this addition correct.
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" .
Dicey Operations for an adult and child. Can you get close to 1000 than your partner?
Watch our videos of multiplication methods that you may not have met before. Can you make sense of them?
How many positive integers less than or equal to 4000 can be written down without using the digits 7, 8 or 9?
Amazing as it may seem the three fives remaining in the following `skeleton' are sufficient to reconstruct the entire long division sum.
Find the values of the nine letters in the sum: FOOT + BALL = GAME
Can you show that 1^99 + 2^99 + 3^99 + 4^99 + 5^99 is divisible by 5?
There are nasty versions of this dice game but we'll start with the nice ones...