Choose four different digits from 1-9 and put one in each box so that the resulting four two-digit numbers add to a total of 100.
Who said that adding couldn't be fun?
Number problems for inquiring primary learners.
There are nasty versions of this dice game but we'll start with the nice ones...
How many solutions can you find to this sum? Each of the different letters stands for a different number.
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?
Find the values of the nine letters in the sum: FOOT + BALL = GAME
Who said that adding, subtracting, multiplying and dividing
couldn't be fun?
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?
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?
Number problems at primary level to work on with others.
The letters in the following addition sum represent the digits 1
... 9. If A=3 and D=2, what number is represented by "CAYLEY"?
Find the sum of all three-digit numbers each of whose digits is
What is the sum of all the digits in all the integers from one to
This activity involves rounding four-digit numbers to the nearest thousand.
Dicey Operations for an adult and child. Can you get close to 1000 than your partner?
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?
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?
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.
A car's milometer reads 4631 miles and the trip meter has 173.3 on
it. How many more miles must the car travel before the two numbers
contain the same digits in the same order?
There are six numbers written in five different scripts. Can you sort out which is which?
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Can you replace the letters with numbers? Is there only one
solution in each case?
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
Each child in Class 3 took four numbers out of the bag. Who had
made the highest even number?
Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.
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 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?
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?
Number problems at primary level that require careful consideration.
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?
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?
This is a game in which your counters move in a spiral round the snail's shell. It is about understanding tens and units.
Number problems at primary level that may require determination.
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
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.
A game to be played against the computer, or in groups. Pick a 7-digit number. A random digit is generated. What must you subract to remove the digit from your number? the first to zero wins.
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" .
Can you substitute numbers for the letters in these sums?
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 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 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
Replace each letter with a digit to make this addition correct.
Can you show that 1^99 + 2^99 + 3^99 + 4^99 + 5^99 is divisible by
Amazing as it may seem the three fives remaining in the following
`skeleton' are sufficient to reconstruct the entire long division
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.