Creating and manipulating expressions and formulae

There are 198 NRICH Mathematical resources connected to Creating and manipulating expressions and formulae
Painted Cube
problem

Painted Cube

Age
14 to 16
Challenge level
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Imagine a large cube made from small red cubes being dropped into a pot of yellow paint. How many of the small cubes will have yellow paint on their faces?
Your number is...
problem

Your number is...

Age
7 to 14
Challenge level
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Think of a number and follow the machine's instructions... I know what your number is! Can you explain how I know?
Perfectly Square
problem

Perfectly Square

Age
14 to 16
Challenge level
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The sums of the squares of three related numbers is also a perfect square - can you explain why?
More Number Pyramids
problem

More Number Pyramids

Age
11 to 14
Challenge level
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When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...
Pair Products
problem

Pair Products

Age
14 to 16
Challenge level
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Choose four consecutive whole numbers. Multiply the first and last numbers together. Multiply the middle pair together. What do you notice?
Circles in Circles
problem

Circles in Circles

Age
16 to 18
Challenge level
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This pattern of six circles contains three unit circles. Work out the radii of the other three circles and the relationship between them.
Special Numbers
problem

Special Numbers

Age
11 to 14
Challenge level
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My two digit number is special because adding the sum of its digits to the product of its digits gives me my original number. What could my number be?
Poly Fibs
problem

Poly Fibs

Age
16 to 18
Challenge level
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A sequence of polynomials starts 0, 1 and each poly is given by combining the two polys in the sequence just before it. Investigate and prove results about the roots of the polys.
Fibonacci Factors
problem

Fibonacci Factors

Age
16 to 18
Challenge level
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For which values of n is the Fibonacci number fn even? Which Fibonnaci numbers are divisible by 3?
Chocolate 2010
problem

Chocolate 2010

Age
14 to 16
Challenge level
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First of all, pick the number of times a week that you would like to eat chocolate. Multiply this number by 2...