Counting

There are 92 NRICH Mathematical resources connected to Counting
Mrs Beeswax
problem

Mrs Beeswax

Age
5 to 7
Challenge level
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In how many ways could Mrs Beeswax put ten coins into her three puddings so that each pudding ended up with at least two coins?
Page Numbers
problem

Page Numbers

Age
7 to 11
Challenge level
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Exactly 195 digits have been used to number the pages in a book. How many pages does the book have?
Euromaths
problem

Euromaths

Age
11 to 14
Challenge level
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How many ways can you write the word EUROMATHS by starting at the top left hand corner and taking the next letter by stepping one step down or one step to the right in a 5x5 array?
Pairs
problem

Pairs

Age
11 to 14
Challenge level
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Ann thought of 5 numbers and told Bob all the sums that could be made by adding the numbers in pairs. The list of sums is 6, 7, 8, 8, 9, 9, 10,10, 11, 12. Help Bob to find out which numbers Ann was thinking of.
Neighbours
problem

Neighbours

Age
7 to 11
Challenge level
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In a square in which the houses are evenly spaced, numbers 3 and 10 are opposite each other. What is the smallest and what is the largest possible number of houses in the square?
How many dice?
problem

How many dice?

Age
11 to 14
Challenge level
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A standard die has the numbers 1, 2 and 3 are opposite 6, 5 and 4 respectively so that opposite faces add to 7? If you make standard dice by writing 1, 2, 3, 4, 5, 6 on blank cubes you will find there are 2 and only 2 different standard dice. Can you prove this ?
Cube Paths
problem

Cube Paths

Age
11 to 14
Challenge level
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Given a 2 by 2 by 2 skeletal cube with one route `down' the cube. How many routes are there from A to B?
Painting Cubes
problem

Painting Cubes

Age
11 to 14
Challenge level
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Imagine you have six different colours of paint. You paint a cube using a different colour for each of the six faces. How many different cubes can be painted using the same set of six colours?
Card Trick 2
problem

Card Trick 2

Age
11 to 14
Challenge level
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Can you explain how this card trick works?
Euler's Officers
problem

Euler's Officers

Age
14 to 16
Challenge level
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How many different ways can you arrange the officers in a square?