Mental calculations

There are 106 NRICH Mathematical resources connected to Mental calculations
The Tall Tower
problem
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The tall tower

Age
5 to 7
Challenge level
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As you come down the ladders of the Tall Tower you collect useful spells. Which way should you go to collect the most spells?
Going round in circles
problem
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Going round in circles

Age
11 to 14
Challenge level
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Mathematicians are always looking for efficient methods for solving problems. How efficient can you be?
Maze 100
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?
What's in a Name?
problem
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What's in a name?

Age
5 to 7
Challenge level
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What do you notice about these squares of numbers? What is the same? What is different?
Which symbol?
problem
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Which symbol?

Age
7 to 11
Challenge level
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Choose a symbol to put into the number sentence.
Noah
problem
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Noah

Age
5 to 7
Challenge level
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Noah saw 12 legs walk by into the Ark. How many creatures did he see?
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.
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?
Mixing Lemonade
problem
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Mixing lemonade

Age
11 to 14
Challenge level
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Can you work out which drink has the stronger flavour?

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.