Reasoning, convincing and proving

There are 458 NRICH Mathematical resources connected to Reasoning, convincing and proving
Concrete wheel
problem

Concrete wheel

Age
11 to 14
Challenge level
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A huge wheel is rolling past your window. What do you see?
Harmonic Triangle
problem

Harmonic Triangle

Age
14 to 16
Challenge level
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Can you see how to build a harmonic triangle? Can you work out the next two rows?
Odds and Evens
problem

Odds and Evens

Age
11 to 14
Challenge level
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Are these games fair? How can you tell?
Trig Rules OK
problem

Trig Rules OK

Age
16 to 18
Challenge level
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Change the squares in this diagram and spot the property that stays the same for the triangles. Explain...
More Total Totality
problem

More Total Totality

Age
11 to 14
Challenge level
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Is it possible to arrange the numbers 1-6 on the nodes of this diagram, so that all the sums between numbers on adjacent nodes are different?
Total Totality
problem

Total Totality

Age
11 to 14
Challenge level
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Is it possible to arrange the numbers 1-6 on the nodes of this diagram, so that all the sums between numbers on adjacent nodes are different?
Day of the Triffids
problem

Day of the Triffids

Age
14 to 16
Challenge level
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Jasmine buys three different types of plant. How many triffids did she buy?
Multiplication square
problem

Multiplication square

Age
14 to 16
Challenge level
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Pick a square within a multiplication square and add the numbers on each diagonal. What do you notice?
Plus or Minus
problem

Plus or Minus

Age
16 to 18
Challenge level
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Make and prove a conjecture about the value of the product of the Fibonacci numbers $F_{n+1}F_{n-1}$.