Number bases

There are 25 NRICH Mathematical resources connected to Number bases
Oh for the mathematics of yesteryear
problem
Favourite

Oh for the mathematics of yesteryear

Age
11 to 14
Challenge level
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A garrison of 600 men has just enough bread ... but, with the news that the enemy was planning an attack... How many ounces of bread a day must each man in the garrison be allowed, to hold out 45 days against the siege of the enemy?
Guesswork
problem
Favourite

Guesswork

Age
14 to 16
Challenge level
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Ask a friend to choose a number between 1 and 63. By identifying which of the six cards contains the number they are thinking of it is easy to tell them what the number is.
More Secret Transmissions
problem

More secret transmissions

Age
16 to 18
Challenge level
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In 'Secret Transmissions', Agent X could send four-digit codes error free. Can you devise an error-correcting system for codes with more than four digits?
Secret Transmissions
problem

Secret transmissions

Age
14 to 16
Challenge level
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How can Agent X transmit data on a faulty line and be sure that her message will get through?
Nim
problem

Nim

Age
14 to 16
Challenge level
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Start with any number of counters in any number of piles. 2 players take it in turns to remove any number of counters from a single pile. The loser is the player who takes the last counter.
Binary Squares
problem

Binary squares

Age
16 to 18
Challenge level
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If a number N is expressed in binary by using only 'ones,' what can you say about its square (in binary)?
Basic Rhythms
problem

Basic rhythms

Age
16 to 18
Challenge level
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Explore a number pattern which has the same symmetries in different bases.
Base Puzzle
problem

Base puzzle

Age
11 to 14
Challenge level
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This investigation is about happy numbers in the World of the Octopus where all numbers are written in base 8 .Octi the octopus counts.
Happy Octopus
problem

Happy octopus

Age
11 to 14
Challenge level
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This investigation is about happy numbers in the World of the Octopus where all numbers are written in base 8 ... Find all the fixed points and cycles for the happy number sequences in base 8.
Basically
problem

Basically

Age
11 to 14
Challenge level
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The number 3723(in base 10) is written as 123 in another base. What is that base?