Multiplication and division

  • Calendar Calculations
    problem

    Calendar Calculations

    Age
    7 to 11
    Challenge level
    Try adding together the dates of all the days in one week. Now multiply the first date by 7 and add 21. Can you explain what happens?
  • Code Breaker
    problem

    Code Breaker

    Age
    7 to 11
    Challenge level
    This problem is based on a code using two different prime numbers less than 10. You'll need to multiply them together and shift the alphabet forwards by the result. Can you decipher the code?
  • Slippy Numbers
    problem

    Slippy Numbers

    Age
    11 to 14
    Challenge level
    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
    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
    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
    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

    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

    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

    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

    Twizzle, a female giraffe, needs transporting to another zoo. Which route will give the fastest journey?

Displaying 111 - 120 of 232