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. . . .
Each child in Class 3 took four numbers out of the bag. Who had made the highest even number?
32 x 38 = 30 x 40 + 2 x 8; 34 x 36 = 30 x 40 + 4 x 6; 56 x 54 = 50 x 60 + 6 x 4; 73 x 77 = 70 x 80 + 3 x 7 Verify and generalise if possible.
When asked how old she was, the teacher replied: My age in years is not prime but odd and when reversed and added to my age you have a perfect square...
Replace each letter with a digit to make this addition correct.
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. . . .
There are six numbers written in five different scripts. Can you sort out which is which?
This is a game in which your counters move in a spiral round the snail's shell. It is about understanding tens and units.
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?
Which is quicker, counting up to 30 in ones or counting up to 300 in tens? Why?
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?
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 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.
What is the sum of all the digits in all the integers from one to one million?
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.
Think of a two digit number, reverse the digits, and add the numbers together. Something special happens...
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.
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?
Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
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?
Follow the clues to find the mystery number.
Number problems at primary level that may require determination.
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.
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?
Exploring the structure of a number square: how quickly can you put the number tiles in the right place on the grid?
This activity involves rounding four-digit numbers to the nearest thousand.
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 two digit numbers (10, 11, . . . ,99). In writing down all these numbers, which digits occur least often, and which occur most often ? What about three digit numbers, four digit numbers. . . .
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" .
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)?
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. . . .
Find the sum of all three-digit numbers each of whose digits is odd.
Four strategy dice games to consolidate pupils' understanding of rounding.
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?
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.
Who said that adding couldn't be fun?
Number problems at primary level that require careful consideration.
Number problems at primary level to work on with others.
Use two dice to generate two numbers with one decimal place. 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
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?
Can you complete this calculation by filling in the missing numbers? In how many different ways can you do it?
Explore the relationship between simple linear functions and their graphs.
What happens when you round these numbers to the nearest whole number?
Can you work out some different ways to balance this equation?