Each time you visit the NRICH site there are usually some activities which are 'live'. This means we are inviting students to send us solutions, and we will publish a selection of them, along with each student's name and their school, a few weeks later. If you'd like to know more about what we're looking for, read this short article.
The last day for submitting solutions to these live problems is Monday 9 June.
Live problems
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problemHeads and feet
Age5 to 7Challenge level
On a farm there were some hens and sheep. Altogether there were 8 heads and 22 feet. How many hens were there?
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problemSealed solution
Age7 to 14Challenge level
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?
Recently solved problems
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problemClimbing conundrum
Age7 to 14Challenge level
Five children are taking part in a climbing competition with three parts, where their score for each part will be multiplied together. Can you see how the leaderboard will change depending on what happens in the final climb of the competition?
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problemDigit discovery
Age7 to 11Challenge level
Here is an interesting property about two sets of digits. Can you work out what the digits might be?
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problemLight the lights
Age5 to 7Challenge level
Investigate which numbers make these lights come on. What is the smallest number you can find that lights up all the lights?
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problemLight the lights again
Age7 to 11Challenge level
Each light in this interactivity turns on according to a rule. What happens when you enter different numbers? Can you work out the rule for each light?
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problemTimes tables shifts
Age7 to 11Challenge level
In this activity, the computer chooses a times table and shifts it. Can you work out the table and the shift each time?