Multiplication and division

  • Adjacent Factors
    problem

    Adjacent Factors

    Age
    11 to 14
    Challenge level
    filled star filled star empty star
    Two numbers can be placed adjacent if one of them divides the other. Using only $1,...,10$, can you write the longest such list?
  • Rolling Along the Trail
    problem

    Rolling Along the Trail

    Age
    11 to 14
    Challenge level
    filled star filled star empty star
    What could be the scores from five throws of this dice?
  • Slippy Numbers
    problem

    Slippy Numbers

    Age
    11 to 14
    Challenge level
    filled star filled star filled star
    The number 10112359550561797752808988764044943820224719 is called a 'slippy number' because, when the last digit 9 is moved to the front, the new number produced is the slippy number multiplied by 9.
  • Eminit
    problem

    Eminit

    Age
    11 to 14
    Challenge level
    filled star filled star filled star
    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?
  • X marks the spot
    problem

    X Marks the Spot

    Age
    11 to 14
    Challenge level
    filled star filled star filled star
    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" .
  • A One in Seven Chance
    problem

    A One in Seven Chance

    Age
    11 to 14
    Challenge level
    filled star filled star filled star
    What is the remainder when 2^{164}is divided by 7?
  • Shut the Box for Two
    game

    Shut the Box for Two

    Age
    5 to 7
    Challenge level
    filled star empty star empty star
    Shut the Box game for an adult and child. Can you turn over the cards which match the numbers on the dice?
  • Starfish Spotting
    problem

    Starfish Spotting

    Age
    5 to 7
    Challenge level
    filled star filled star empty star

    How many starfish could there be on the beach, and how many children, if I can see 28 arms?

  • What's Left?
    problem

    What's Left?

    Age
    5 to 7
    Challenge level
    filled star filled star empty star
    Use this grid to shade the numbers in the way described. Which numbers do you have left? Do you know what they are called?
  • Twizzle's Journey
    problem

    Twizzle's Journey

    Age
    5 to 7
    Challenge level
    filled star filled star filled star
    Twizzle, a female giraffe, needs transporting to another zoo. Which route will give the fastest journey?