Imagine we have four bags containing numbers from a sequence. What numbers can we make now?
Got It game for an adult and child. How can you play so that you know you will always win?
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?
A three digit number abc is always divisible by 7 when 2a+3b+c is divisible by 7. Why?
Imagine we have four bags containing a large number of 1s, 4s, 7s and 10s. What numbers can we make?
Make a set of numbers that use all the digits from 1 to 9, once and once only. Add them up. The result is divisible by 9. Add each of the digits in the new number. What is their sum? Now try some. . . .
List any 3 numbers. It is always possible to find a subset of adjacent numbers that add up to a multiple of 3. Can you explain why and prove it?
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.
Find some examples of pairs of numbers such that their sum is a factor of their product. eg. 4 + 12 = 16 and 4 × 12 = 48 and 16 is a factor of 48.
Can you explain the strategy for winning this game with any target?
How many noughts are at the end of these giant numbers?
In how many ways can the number 1 000 000 be expressed as the product of three positive integers?
Here is a Sudoku with a difference! Use information about lowest common multiples to help you solve it.
Find the smallest positive integer N such that N/2 is a perfect cube, N/3 is a perfect fifth power and N/5 is a perfect seventh power.
You are given the Lowest Common Multiples of sets of digits. Find the digits and then solve the Sudoku.
115^2 = (110 x 120) + 25, that is 13225 895^2 = (890 x 900) + 25, that is 801025 Can you explain what is happening and generalise?
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. . . .
This article takes the reader through divisibility tests and how they work. An article to read with pencil and paper to hand.
Can you convince me of each of the following: If a square number is multiplied by a square number the product is ALWAYS a square number...
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.
Prove that if a^2+b^2 is a multiple of 3 then both a and b are multiples of 3.
Find the largest integer which divides every member of the following sequence: 1^5-1, 2^5-2, 3^5-3, ... n^5-n.
The nth term of a sequence is given by the formula n^3 + 11n . Find the first four terms of the sequence given by this formula and the first term of the sequence which is bigger than one million. . . .
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.
Given the products of diagonally opposite cells - can you complete this Sudoku?
Factors and Multiples game for an adult and child. How can you make sure you win this game?
Can you work out what size grid you need to read our secret message?
Prove that if the integer n is divisible by 4 then it can be written as the difference of two squares.
Make a line of green and a line of yellow rods so that the lines differ in length by one (a white rod)
What is the remainder when 2^2002 is divided by 7? What happens with different powers of 2?
Caroline and James pick sets of five numbers. Charlie chooses three of them that add together to make a multiple of three. Can they stop him?
Helen made the conjecture that "every multiple of six has more factors than the two numbers either side of it". Is this conjecture true?
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?
A game in which players take it in turns to choose a number. Can you block your opponent?
Arrange the four number cards on the grid, according to the rules, to make a diagonal, vertical or horizontal line.
The items in the shopping basket add and multiply to give the same amount. What could their prices be?
Consider numbers of the form un = 1! + 2! + 3! +...+n!. How many such numbers are perfect squares?
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?
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.
Each letter represents a different positive digit AHHAAH / JOKE = HA What are the values of each of the letters?
How many integers between 1 and 1200 are NOT multiples of any of the numbers 2, 3 or 5?
Can you find any perfect numbers? Read this article to find out more...
Find the highest power of 11 that will divide into 1000! exactly.
Which pairs of cogs let the coloured tooth touch every tooth on the other cog? Which pairs do not let this happen? Why?
Substitution and Transposition all in one! How fiendish can these codes get?
Follow this recipe for sieving numbers and see what interesting patterns emerge.
How did the the rotation robot make these patterns?
Gabriel multiplied together some numbers and then erased them. Can you figure out where each number was?
Can you find any two-digit numbers that satisfy all of these statements?
Factor track is not a race but a game of skill. The idea is to go round the track in as few moves as possible, keeping to the rules.