   1 (one;  or , also called "unity" or, in technical contexts, "monad") is a number, a numeral, and the name of the glyph representing that number. it represents a single entity, the unit of counting or measurement. for example, a line segment of "unit length" is a line segment of length 1. ==as a number== one, sometimes referred to as unity, is the integer before two and after zero. one is the first non-zero number in the natural numbers as well as the first odd number in the natural numbers. any number multiplied by one is that number, as one is the identity for multiplication. as a result, one is its own factorial, its own square, its own cube, and so on. one is also the empty product, as any number multiplied by one is itself. it is also the only natural number that is neither composite nor prime with respect to division, but instead considered a unit. ==as a digit== thumb|left the glyph used today in the western world to represent the number 1, a vertical line, often with a serif at the top and sometimes a short horizontal line at the bottom, traces its roots back to the [[india
1_(number) Integers