Linked from
The 35 pages that link to Positional notation, each with the reason it gives.
Binary numberNarrower topic: Binary uses positional notation, with each place worth a power of two.
Binary numeral systemNarrower topic: Binary assigns each position a successive power of two.
SexagesimalNarrower topic: Sexagesimal assigns successive positions powers of 60.
HexadecimalNarrower topic: Hexadecimal assigns each position a successive power of 16.