Find the sum of all three-digit numbers each of whose digits is odd.
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?
Who said that adding couldn't be fun?
Number problems at primary level that may require determination.
Number problems at primary level that require careful consideration.
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.
What happens when you round these three-digit numbers to the nearest 100?
Can you substitute numbers for the letters in these sums?
Use two dice to generate two numbers with one decimal place. What happens when you round these numbers to the nearest whole number?
What do the digits in the number fifteen add up to? How many other numbers have digits with the same total but no zeros?
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?
In the multiplication calculation, some of the digits have been replaced by letters and others by asterisks. Can you reconstruct the original multiplication?
Can you replace the letters with numbers? Is there only one solution in each case?
Number problems at primary level to work on with others.
What happens when you round these numbers to the nearest whole number?
Follow the clues to find the mystery number.
Have a go at balancing this equation. Can you find different ways of doing it?
This activity involves rounding four-digit numbers to the nearest thousand.
Can you complete this calculation by filling in the missing numbers? In how many different ways can you do it?
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?
This 100 square jigsaw is written in code. It starts with 1 and ends with 100. Can you build it up?
Can you work out some different ways to balance this equation?
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?
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?
Replace each letter with a digit to make this addition correct.
Some Games That May Be Nice or Nasty for an adult and child. Use your knowledge of place value to beat your opponent.
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?
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?
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?
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 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 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?
What is the sum of all the digits in all the integers from one to one million?
This is a game in which your counters move in a spiral round the snail's shell. It is about understanding tens and units.
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?
Number problems for inquiring primary learners.
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.
How many solutions can you find to this sum? Each of the different letters stands for a different number.
Each child in Class 3 took four numbers out of the bag. Who had made the highest even number?
How many six digit numbers are there which DO NOT contain a 5?
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. . . .
Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.
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)?
Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Dicey Operations for an adult and child. Can you get close to 1000 than your partner?
Find the values of the nine letters in the sum: FOOT + BALL = GAME
How many positive integers less than or equal to 4000 can be written down without using the digits 7, 8 or 9?
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.