For any number x:
1+1 can have over 10 different results: 0, 1, 2, 10, 110, 11, 10.01, 3, 1100 or "11".
One cannot be used as the base of a numeral system in the ordinary way. Sometimes tallying[?] is referred to as "base 1", since only one mark (the tally) is needed, but this doesn't work in the same way as the usual numeral systems. Related to this, one cannot take logarithms with base 1 (same as one cannot divide by zero, since logn x is loge x / loge n, and log 1 = 0).
One is not always thought of as a number, although (unlike zero) it has been accepted as such since antiquity. Reflecting this, many languages retain a distinction between singular and plural forms of a noun, the former reserved for the case when only one object is being referred to.
Many human cultures have given the concept of one-ness symbolic meanings:
One is also:
Something is unique if it is the only one of its kind. More loosely and exaggeratingly (especially in advertising) the term is used for something very special.