Reasoning, convincing and proving

There are 514 NRICH Mathematical resources connected to Reasoning, convincing and proving
Number rules - OK
problem
Favourite

Number rules - ok

Age
14 to 16
Challenge level
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Can you produce convincing arguments that a selection of statements about numbers are true?
Shopping Basket
problem
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Shopping basket

Age
11 to 16
Challenge level
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The items in the shopping basket add and multiply to give the same amount. What could their prices be?
Shadow Play
problem
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Shadow play

Age
5 to 7
Challenge level
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Here are shadows of some 3D shapes. What shapes could have made them?

Growing Garlic
problem
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Growing garlic

Age
5 to 11
Challenge level
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Ben and his mum are planting garlic. Can you find out how many cloves of garlic they might have had?

Mechanical Integration
problem
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Mechanical integration

Age
16 to 18
Challenge level
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To find the integral of a polynomial, evaluate it at some special points and add multiples of these values.
American Billions
problem
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American billions

Age
11 to 14
Challenge level
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Play the divisibility game to create numbers in which the first two digits make a number divisible by 2, the first three digits make a number divisible by 3...
Marbles in a box
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Marbles in a box

Age
11 to 16
Challenge level
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How many winning lines can you make in a three-dimensional version of noughts and crosses?
Square Corners
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Square corners

Age
7 to 11
Challenge level
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What is the greatest number of counters you can place on the grid below without four of them lying at the corners of a square?

Make 37 Poster
problem
Favourite

Make 37

Age
5 to 11
Challenge level
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Four bags contain a large number of 1s, 3s, 5s and 7s. Can you pick any ten numbers from the bags so that their total is 37?

The Tall Tower
problem
Favourite

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?