Odd and even numbers

There are 75 NRICH Mathematical resources connected to Odd and even numbers
What Could \It Be?
problem
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What could it be?

Age
5 to 7
Challenge level
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In this calculation, the box represents a missing digit. What could the digit be? What would the solution be in each case?
Play to 37
problem
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Play to 37

Age
7 to 11
Challenge level
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In this game for two players, the idea is to take it in turns to choose 1, 3, 5 or 7. The winner is the first to make the total 37.
Sorting the Numbers
problem
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Sorting the numbers

Age
7 to 11
Challenge level
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Can you put the numbers in the correct place in this Carroll diagram?
Magic Letters
problem
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Magic letters

Age
11 to 14
Challenge level
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Charlie has made a Magic V. Can you use his example to make some more? And how about Magic Ls, Ns and Ws?
Two numbers under the microscope
problem
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Two numbers under the microscope

Age
5 to 7
Challenge level
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This investigates one particular property of number by looking closely at an example of adding two odd numbers together.
Odd times Even
problem
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Odd times even

Age
5 to 7
Challenge level
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This problem looks at how one example of your choice can show something about the general structure of multiplication.
Take three numbers
problem
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Take three numbers

Age
7 to 11
Challenge level
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What happens when you add three numbers together? Will your answer be odd or even? How do you know?

Square subtraction
problem
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Square subtraction

Age
7 to 11
Challenge level
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Look at what happens when you take a number, square it and subtract your answer. What kind of number do you get? Can you prove it?
Odds, Evens and More Evens
problem
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Odds, evens and more evens

Age
11 to 14
Challenge level
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Alison, Bernard and Charlie have been exploring sequences of odd and even numbers, which raise some intriguing questions...

Odds and Evens
problem
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Odds and evens

Age
11 to 14
Challenge level
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Are these games fair? How can you tell?