Combinations

There are 149 NRICH Mathematical resources connected to Combinations
Ladybirds in the Garden
problem

Ladybirds in the Garden

Age
5 to 7
Challenge level
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In Sam and Jill's garden there are two sorts of ladybirds with 7 spots or 4 spots. What numbers of total spots can you make?
Sealed Solution
problem

Sealed Solution

Age
7 to 11
Challenge level
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Ten cards are put into five envelopes so that there are two cards in each envelope. The sum of the numbers inside it is written on each envelope. What numbers could be inside the envelopes?
Penta Primes
problem

Penta Primes

Age
7 to 11
Challenge level
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Using all ten cards from 0 to 9, rearrange them to make five prime numbers. Can you find any other ways of doing it?
Penta Post
problem

Penta Post

Age
7 to 11
Challenge level
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Here are the prices for 1st and 2nd class mail within the UK. You have an unlimited number of each of these stamps. Which stamps would you need to post a parcel weighing 825g?
Throw a 100
problem

Throw a 100

Age
7 to 11
Challenge level
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Can you score 100 by throwing rings on this board? Is there more than way to do it?
Plates of Biscuits
problem

Plates of Biscuits

Age
7 to 11
Challenge level
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Can you rearrange the biscuits on the plates so that the three biscuits on each plate are all different and there is no plate with two biscuits the same as two biscuits on another plate?
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?
Cross-Country Race
problem

Cross-Country Race

Age
14 to 16
Challenge level
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Eight children enter the autumn cross-country race at school. How many possible ways could they come in at first, second and third places?
1 Step 2 Step
problem

1 Step 2 Step

Age
11 to 14
Challenge level
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Liam's house has a staircase with 12 steps. He can go down the steps one at a time or two at time. In how many different ways can Liam go down the 12 steps?
Add 3 Dice
problem

Add 3 Dice

Age
7 to 11
Challenge level
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Three dice are placed in a row. Find a way to turn each one so that the three numbers on top of the dice total the same as the three numbers on the front of the dice. Can you find all the ways to do this?