Mental calculations

  • An Easy Way to Multiply by 10?
    problem
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    An Easy Way to Multiply by 10?

    Age
    7 to 11
    Challenge level
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    Do you agree with Badger's statements? Is Badger's reasoning 'watertight'? Why or why not?

  • Roll these Dice
    problem
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    Roll These Dice

    Age
    7 to 11
    Challenge level
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    Roll two red dice and a green dice. Add the two numbers on the red dice and take away the number on the green. What are all the different possible answers?

  • problem
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    Maze 100

    Age
    7 to 11
    Challenge level
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    Can you go through this maze so that the numbers you pass add to exactly 100?

  • Domino Square
    problem
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    Domino Square

    Age
    7 to 11
    Challenge level
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    Use the 'double-3 down' dominoes to make a square so that each side has eight dots.

  • Make 100
    problem
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    Make 100

    Age
    7 to 11
    Challenge level
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    Find at least one way to put in some operation signs to make these digits come to 100.

  • Twenty Divided into Six
    problem
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    Twenty Divided Into Six

    Age
    7 to 11
    Challenge level
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    Katie had a pack of 20 cards numbered from 1 to 20. She arranged the cards into 6 unequal piles where each pile added to the same total. What was the total and how could this be done?

  • Shapes on the Playground
    problem
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    Shapes on the Playground

    Age
    7 to 11
    Challenge level
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    Sally and Ben were drawing shapes in chalk on the school playground. Can you work out what shapes each of them drew using the clues?

  • Finding Fifteen
    problem
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    Finding Fifteen

    Age
    7 to 11
    Challenge level
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    Tim had nine cards each with a different number from 1 to 9 on it. How could he have put them into three piles so that the total in each pile was 15?

  • Six Numbered Cubes
    problem
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    Six Numbered Cubes

    Age
    7 to 11
    Challenge level
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    This task combines spatial awareness with addition and multiplication.

  • Countdown
    game
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    Countdown

    Age
    7 to 14
    Challenge level
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    Here is a chance to play a version of the classic Countdown Game.