Number bases

There are 25 NRICH Mathematical resources connected to Number bases
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?
Back to Basics
problem

Back to basics

Age
14 to 16
Challenge level
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Find b where 3723(base 10) = 123(base b).
Back to the Planet of Vuvv
problem

Back to the planet of vuvv

Age
11 to 14
Challenge level
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There are two forms of counting on Vuvv - Zios count in base 3 and Zepts count in base 7. One day four of these creatures, two Zios and two Zepts, sat on the summit of a hill to count the legs of the creatures they could see. The creature looking to the West wrote 122. The creature looking to the East wrote 22. The creature looking to the South wrote 101. The creature looking to the North wrote 41. In which direction are the 2 Zios looking and in which directions are the 2 Zepts looking?
Phew I'm Factored
problem

Phew i'm factored

Age
14 to 16
Challenge level
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Explore the factors of the numbers which are written as 10101 in different number bases. Prove that the numbers 10201, 11011 and 10101 are composite in any base.