Addition and subtraction

  • Oranges and Lemons
    problem

    Oranges and Lemons

    Age
    7 to 11
    Challenge level
    On the table there is a pile of oranges and lemons that weighs exactly one kilogram. Using the information, can you work out how many lemons there are?
  • Back to School
    problem

    Back to School

    Age
    7 to 11
    Challenge level
    Mr. Sunshine tells the children they will have 2 hours of homework. After several calculations, Harry says he hasn't got time to do this homework. Can you see where his reasoning is wrong?
  • Dividing a Cake
    problem

    Dividing a Cake

    Age
    7 to 11
    Challenge level
    Annie cut this numbered cake into 3 pieces with 3 cuts so that the numbers on each piece added to the same total. Where were the cuts and what fraction of the whole cake was each piece?
  • Penta Post
    problem

    Penta Post

    Age
    7 to 11
    Challenge level
    Here are the prices for 1st and 2nd class mail within the UK. You have an unlimited number of each of these stamps. Which stamps would you need to post a parcel weighing 825g?
  • The Clockmaker's Birthday Cake
    problem

    The Clockmaker's Birthday Cake

    Age
    7 to 11
    Challenge level
    The clockmaker's wife cut up his birthday cake to look like a clock face. Can you work out who received each piece?
  • Reverse trick
    problem

    Reverse Trick

    Age
    7 to 11
    Challenge level
    Tell your friends that you have a strange calculator that turns numbers backwards. What secret number do you have to enter to make 141 414 turn around?
  • Sisters and Brothers
    problem

    Sisters and Brothers

    Age
    7 to 11
    Challenge level
    Cassandra, David and Lachlan are brothers and sisters. They range in age between 1 year and 14 years. Can you figure out their exact ages from the clues?
  • Clock Face
    problem

    Clock Face

    Age
    7 to 11
    Challenge level

    Where can you draw a line on a clock face so that the numbers on both sides have the same total?

  • Gift Stacks
    problem

    Gift Stacks

    Age
    7 to 11
    Challenge level
    Use the information to work out how many gifts there are in each pile.
  • Number Tracks
    problem

    Number Tracks

    Age
    7 to 11
    Challenge level

    Ben's class were cutting up number tracks. First they cut them into twos and added up the numbers on each piece. What patterns could they see?

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