Addition and subtraction

  • Small tomato seedlings in pink pots.
    problem

    Negative Dice

    Age
    11 to 14
    Challenge level

    If the odd numbers on two dice are made negative, which of the totals cannot be achieved?

  • Multiply the Addition Square
    problem

    Multiply the Addition Square

    Age
    11 to 14
    Challenge level

    If you take a three by three square on a 1-10 addition square and multiply the diagonally opposite numbers together, what is the difference between these products. Why?

  • Small tomato seedlings in pink pots.
    problem

    Calculation 2000

    Age
    11 to 14
    Challenge level

    Weekly Problem 49 - 2013
    What is the value of 2000 + 1999 × 2000?

  • Small tomato seedlings in pink pots.
    problem

    Reverse Subtraction

    Age
    11 to 14
    Challenge level

    What is the value of c in this subtraction?

  • Small tomato seedlings in pink pots.
    problem

    Debt Recovery

    Age
    11 to 14
    Challenge level

    Tony and Tina can't work out which of them owes what to the other. Can you?

  • Small tomato seedlings in pink pots.
    problem

    Little Goldbach

    Age
    11 to 14
    Challenge level

    How many of the numbers 1 to 20 are not the sum of two primes?

  • Small tomato seedlings in pink pots.
    problem

    Mathematical Ages

    Age
    11 to 14
    Challenge level

    Arrange these three famous mathematicians in order with the shortest-lived first.

  • Small tomato seedlings in pink pots.
    problem

    Bus Route

    Age
    11 to 14
    Challenge level

    How far apart are the first and last bus stops in this bus route?

  • Small tomato seedlings in pink pots.
    problem

    Debasing the Coinage

    Age
    11 to 14
    Challenge level

    How much lighter will £5 worth of 5p's be with these new lighter coins?

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