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Rulers start at zero: At zero centimetres, you have nothing, whereas at one centimetres, you have one unit of length. Memory is similar: You start filling at the beginning (zero), hence, the first x-memory units contain x units of data, the next unit contains unit x+1.


2

Think about human ages. Babies that are newly born are at age 0. That's zero-based indexing.


1

Distances in boardgames with discrete spaces. For example: Chess, wargames, Dungeons & Dragons played on a battlemap, etc. Counting movement, the space you start in counts as space zero (or more accurately: if a piece stays in the same space, then it has moved zero distance). There are a number of situations in wargames and RPGs where two pieces might ...


1

The ground floor is the de facto 0th floor. Humans are born at age 0. Military time starts at 0:00. Despite the day having 24 hours, it is not correct to write 24:00. As a side-note, Japanese TV uses 0-indexed 12-hour notation. That means 11 AM is followed by 0 PM, not 12 PM.


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