Combinations

There are 149 NRICH Mathematical resources connected to Combinations
Chocs, Mints, Jellies
problem

Chocs, Mints, Jellies

Age
7 to 11
Challenge level
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In a bowl there are 4 Chocolates, 3 Jellies and 5 Mints. Find a way to share the sweets between the three children so they each get the kind they like. Is there more than one way to do it?
Rod Measures
problem

Rod Measures

Age
7 to 11
Challenge level
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Using 3 rods of integer lengths, none longer than 10 units and not using any rod more than once, you can measure all the lengths in whole units from 1 to 10 units. How many ways can you do this?
Clocked
problem

Clocked

Age
11 to 14
Challenge level
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Is it possible to rearrange the numbers 1,2......12 around a clock face in such a way that every two numbers in adjacent positions differ by any of 3, 4 or 5 hours?
Beads
problem

Beads

Age
7 to 11
Challenge level
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Three beads are threaded on a circular wire and are coloured either red or blue. Can you find all four different combinations?
Two on Five
problem

Two on Five

Age
5 to 11
Challenge level
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Take 5 cubes of one colour and 2 of another colour. How many different ways can you join them if the 5 must touch the table and the 2 must not touch the table?
Elf Suits
problem

Elf Suits

Age
7 to 11
Challenge level
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If these elves wear a different outfit every day for as many days as possible, how many days can their fun last?
Magic triangle
problem

Magic triangle

Age
7 to 11
Challenge level
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Place the digits 1 to 9 into the circles so that each side of the triangle adds to the same total.
Even Up
problem

Even Up

Age
11 to 14
Challenge level
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Consider all of the five digit numbers which we can form using only the digits 2, 4, 6 and 8. If these numbers are arranged in ascending order, what is the 512th number?
Take Three From Five
problem

Take Three From Five

Age
11 to 16
Challenge level
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Caroline and James pick sets of five numbers. Charlie tries to find three that add together to make a multiple of three. Can they stop him?
Six times five
problem

Six times five

Age
11 to 14
Challenge level
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How many six digit numbers are there which DO NOT contain a 5?