Factors, Multiples and Primes: Age 11-16

This is part of our collection of favourite rich tasks arranged by topic.

If you are a teacher, you can find the whole collection on our Secondary Curriculum teacher page.
Alternatively, if you are a student, you'll find the same problems on our Secondary Curriculum student page.


  • Dozens
    problem
    Favourite

    Dozens

    Age
    7 to 14
    Challenge level
    1 out of 3

    Can you select the missing digit(s) to find the largest multiple?

  • Factors and Multiples Game
    game
    Favourite

    Factors and Multiples Game

    Age
    7 to 16
    Challenge level
    1 out of 3

    A game in which players take it in turns to choose a number. Can you block your opponent?

  • Xavi's T-shirt
    problem
    Favourite

    Xavi's T-Shirt

    Age
    7 to 16
    Challenge level
    1 out of 3

    How much can you read into a T-shirt?

  • An American flag waving in the wind.
    problem
    Favourite

    American Billions

    Age
    11 to 14
    Challenge level
    1 out of 3

    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...

  • Multiples Sudoku
    problem
    Favourite

    Multiples Sudoku

    Age
    11 to 14
    Challenge level
    1 out of 3

    Each clue in this Sudoku is the product of the two numbers in adjacent cells.

  • How much can we spend?
    problem
    Favourite

    How Much Can We Spend?

    Age
    11 to 14
    Challenge level
    1 out of 3

    A country has decided to have just two different coins. Which totals can be made? Is there a largest total that cannot be made? How do you know?

  • Diminishing Returns
    problem
    Favourite

    Diminishing Returns

    Age
    11 to 14
    Challenge level
    1 out of 3

    How much of the square is coloured blue? How will the pattern continue?

  • Sieve of Eratosthenes
    problem
    Favourite

    Sieve of Eratosthenes

    Age
    11 to 14
    Challenge level
    1 out of 3

    Follow this recipe for sieving numbers and see what interesting patterns emerge.

  • Gabriel's Problem
    problem
    Favourite

    Gabriel's Problem

    Age
    11 to 14
    Challenge level
    1 out of 3

    Gabriel multiplied together some numbers and then erased them. Can you figure out where each number was?

  • Number Families
    problem
    Favourite

    Number Families

    Age
    11 to 14
    Challenge level
    1 out of 3

    How many different number families can you find?

  • Counting Factors
    problem
    Favourite

    Counting Factors

    Age
    11 to 14
    Challenge level
    2 out of 3

    Is there an efficient way to work out how many factors a large number has?

  • Stars
    problem
    Favourite

    Stars

    Age
    11 to 14
    Challenge level
    2 out of 3

    Can you work out what step size to take to ensure you visit all the dots on the circle?

  • Factors and Multiples Puzzle
    problem
    Favourite

    Factors and Multiples Puzzle

    Age
    11 to 14
    Challenge level
    2 out of 3

    Using your knowledge of the properties of numbers, can you fill all the squares on the board?

  • Route to infinity
    problem
    Favourite

    Route to Infinity

    Age
    11 to 14
    Challenge level
    2 out of 3

    Can you describe this route to infinity? Where will the arrows take you next?

  • Power mad!
    problem
    Favourite

    Power Mad!

    Age
    11 to 14
    Challenge level
    2 out of 3

    Powers of numbers behave in surprising ways. Take a look at some of these and try to explain why they are true.

  • A blue patchwork quilt draped over a white sofa.
    problem
    Favourite

    Alison's Quilt

    Age
    11 to 14
    Challenge level
    2 out of 3

    Nine squares are fitted together to form a rectangle. Can you find its dimensions?

  • Four playing cards on top of each other. Each card shows a different ace.
    problem
    Favourite

    Snappy Statements

    Age
    11 to 14
    Challenge level
    2 out of 3

    Use properties of numbers to work out whether you can satisfy all these statements at the same time.

  • Differences
    problem
    Favourite

    Differences

    Age
    11 to 14
    Challenge level
    3 out of 3

    Can you guarantee that, for any three numbers you choose, the product of their differences will always be an even number?

  • Divisibility Tests
    article

    Divisibility Tests

    This article explains various divisibility rules and why they work. An article to read with pencil and paper handy.

  • Multiple Surprises
    problem
    Favourite

    Multiple Surprises

    Age
    11 to 16
    Challenge level
    1 out of 3

    Sequences of multiples keep cropping up...

  • Funny Factorisation
    problem
    Favourite

    Funny Factorisation

    Age
    11 to 16
    Challenge level
    2 out of 3

    Using the digits 1 to 9, the number 4396 can be written as the product of two numbers. Can you find the factors?

  • Take Three From Five
    problem
    Favourite

    Take Three From Five

    Age
    11 to 16
    Challenge level
    2 out of 3

    Caroline and James pick sets of five numbers. Charlie tries to find three that add together to make a multiple of three. Can they stop him?

  • Product Sudoku
    problem
    Favourite

    Product Sudoku

    Age
    11 to 16
    Challenge level
    2 out of 3

    The clues for this Sudoku are the product of the numbers in adjacent squares.

  • problem
    Favourite

    Shopping Basket

    Age
    11 to 16
    Challenge level
    3 out of 3

    The items in the shopping basket add and multiply to give the same amount. What could their prices be?

  • Beelines
    problem
    Favourite

    Beelines

    Age
    14 to 16
    Challenge level
    1 out of 3

    Is there a relationship between the coordinates of the endpoints of a line and the number of grid squares it crosses?

  • Expenses
    problem
    Favourite

    Expenses

    Age
    14 to 16
    Challenge level
    2 out of 3

    What is the largest number which, when divided into these five numbers in turn, leaves the same remainder each time?

  • Filling the gaps
    problem
    Favourite

    Filling the Gaps

    Age
    14 to 16
    Challenge level
    2 out of 3

    Which numbers can we write as a sum of square numbers?

  • Latin Numbers
    problem
    Favourite

    Latin Numbers

    Age
    14 to 16
    Challenge level
    3 out of 3

    Can you create a Latin Square from multiples of a six digit number?

  • LCM Sudoku
    problem
    Favourite

    LCM Sudoku

    Age
    14 to 16
    Challenge level
    3 out of 3

    Here is a Sudoku with a difference! Use information about lowest common multiples to help you solve it.