Reasoning, convincing and proving

There are 458 NRICH Mathematical resources connected to Reasoning, convincing and proving
Continued Fractions II
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Continued Fractions II

In this article we show that every whole number can be written as a continued fraction of the form k/(1+k/(1+k/...)).
The Frieze Tree
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The Frieze Tree

Patterns that repeat in a line are strangely interesting. How many types are there and how do you tell one type from another?
Transitivity
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Transitivity

Suppose A always beats B and B always beats C, then would you expect A to beat C? Not always! What seems obvious is not always true. Results always need to be proved in mathematics.
Sums of Squares and Sums of Cubes
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Sums of Squares and Sums of Cubes

An account of methods for finding whether or not a number can be written as the sum of two or more squares or as the sum of two or more cubes.
Magic Squares II
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Magic Squares II

An article which gives an account of some properties of magic squares.
Why stop at Three by One
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Why stop at Three by One

Beautiful mathematics. Two 18 year old students gave eight different proofs of one result then generalised it from the 3 by 1 case to the n by 1 case and proved the general result.
Picturing Pythagorean Triples
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Picturing Pythagorean Triples

This article discusses how every Pythagorean triple (a, b, c) can be illustrated by a square and an L shape within another square. You are invited to find some triples for yourself.