Filter by: Content type: ALL Problems Articles Games Stage: All Stage 1&2 Stage 2&3 Stage 3&4 Stage 4&5 Challenge level:
Make a line of green and a line of yellow rods so that the lines differ in length by one (a white rod)
A game in which players take it in turns to choose a number. Can you block your opponent?
Can you find a relationship between the number of dots on the circle and the number of steps that will ensure that all points are hit?
Take any pair of numbers, say 9 and 14. Take the larger number, fourteen, and count up in 14s. Then divide each of those values by the 9, and look at the remainders.
A challenge that requires you to apply your knowledge of the properties of numbers. Can you fill all the squares on the board?
Given the products of adjacent cells, can you complete this Sudoku?
Follow this recipe for sieving numbers and see what interesting patterns emerge.
Using the digits 1, 2, 3, 4, 5, 6, 7 and 8, mulitply a two two digit numbers are multiplied to give a four digit number, so that the expression is correct. How many different solutions can you find?
Ben passed a third of his counters to Jack, Jack passed a quarter of his counters to Emma and Emma passed a fifth of her counters to Ben. After this they all had the same number of counters.
6! = 6 x 5 x 4 x 3 x 2 x 1. The highest power of 2 that divides exactly into 6! is 4 since (6!) / (2^4 ) = 45. What is the highest power of two that divides exactly into 100!?
Complete the following expressions so that each one gives a four digit number as the product of two two digit numbers and uses the digits 1 to 8 once and only once.
Data is sent in chunks of two different sizes - a yellow chunk has 5 characters and a blue chunk has 9 characters. A data slot of size 31 cannot be exactly filled with a combination of yellow and. . . .
Find the highest power of 11 that will divide into 1000! exactly.
In how many ways can the number 1 000 000 be expressed as the product of three positive integers?
This package contains a collection of problems from the NRICH website that could be suitable for students who have a good understanding of Factors and Multiples and who feel ready to take on some. . . .
The number 12 = 2^2 × 3 has 6 factors. What is the smallest natural number with exactly 36 factors?
Play the divisibility game to create numbers in which the first two digits make a number divisible by 2, the first three digits make a number divisible by 3...
A student in a maths class was trying to get some information from her teacher. She was given some clues and then the teacher ended by saying, "Well, how old are they?"
How many integers between 1 and 1200 are NOT multiples of any of the numbers 2, 3 or 5?
The sum of the first 'n' natural numbers is a 3 digit number in which all the digits are the same. How many numbers have been summed?
A game for two people, or play online. Given a target number, say 23, and a range of numbers to choose from, say 1-4, players take it in turns to add to the running total to hit their target.
A mathematician goes into a supermarket and buys four items. Using a calculator she multiplies the cost instead of adding them. How can her answer be the same as the total at the till?
I put eggs into a basket in groups of 7 and noticed that I could easily have divided them into piles of 2, 3, 4, 5 or 6 and always have one left over. How many eggs were in the basket?
Can you find what the last two digits of the number $4^{1999}$ are?
For this challenge, you'll need to play Got It! Can you explain the strategy for winning this game with any target?
What is the smallest number of answers you need to reveal in order to work out the missing headers?
A number N is divisible by 10, 90, 98 and 882 but it is NOT divisible by 50 or 270 or 686 or 1764. It is also known that N is a factor of 9261000. What is N?
Which pairs of cogs let the coloured tooth touch every tooth on the other cog? Which pairs do not let this happen? Why?
Can you work out what size grid you need to read our secret message?
Find some triples of whole numbers a, b and c such that a^2 + b^2 + c^2 is a multiple of 4. Is it necessarily the case that a, b and c must all be even? If so, can you explain why?
Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?
The number 8888...88M9999...99 is divisible by 7 and it starts with the digit 8 repeated 50 times and ends with the digit 9 repeated 50 times. What is the value of the digit M?
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Substitution and Transposition all in one! How fiendish can these codes get?
Rectangles are considered different if they vary in size or have different locations. How many different rectangles can be drawn on a chessboard?
Three people chose this as a favourite problem. It is the sort of problem that needs thinking time - but once the connection is made it gives access to many similar ideas.
Here is a machine with four coloured lights. Can you develop a strategy to work out the rules controlling each light?
Can you find any perfect numbers? Read this article to find out more...
The clues for this Sudoku are the product of the numbers in adjacent squares.
A game that tests your understanding of remainders.
Imagine we have four bags containing numbers from a sequence. What numbers can we make now?
You are given the Lowest Common Multiples of sets of digits. Find the digits and then solve the Sudoku.
Can you find a way to identify times tables after they have been shifted up?
Find a cuboid (with edges of integer values) that has a surface area of exactly 100 square units. Is there more than one? Can you find them all?
The puzzle can be solved by finding the values of the unknown digits (all indicated by asterisks) in the squares of the $9\times9$ grid.
Twice a week I go swimming and swim the same number of lengths of the pool each time. As I swim, I count the lengths I've done so far, and make it into a fraction of the whole number of lengths. . . .
Each letter represents a different positive digit AHHAAH / JOKE = HA What are the values of each of the letters?
In this activity, the computer chooses a times table and shifts it. Can you work out the table and the shift each time?
Explore the relationship between simple linear functions and their graphs.
Given the products of diagonally opposite cells - can you complete this Sudoku?