One

   One (1, also a unit) is the first positive whole [1]number, signifying the
   existence of a single unique object we're counting.

   Some facts about this number include:

     * It is an [2]odd number.
     * It is a positive number, whole number (integer), [3]real number,
       [4]rational number and [5]complex number.
     * It is by convention NOT a [6]prime number, though it is only divisible
       by 1 and itself.
     * It is a multiplicative identity, i.e. 1 * x = x for any number x. Also
       x / 1 = x, x^1 = x, 1^x = 1 for any number x.
     * In programming there is a very common type of [7]bug called [8]off by
       one in which a boundary is either incorrectly included or excluded.
     * 1 is often a convenient upper bound of many intervals, e.g. when
       [9]normalizing numbers or dealing with [10]probabilities.
     * In computing the number and digit 1, as opposed to [11]0, usually
       means the true or on value.
     * In programming operations with 1 (similarly to [12]0) are very common
       and may sometimes be handled as special cases to help efficiency, for
       example adding or subtracting one is called incrementing and
       decrementing and many [13]assembly languages have special instructions
       for this.

Links:
1. number.md
2. odd.md
3. real_number.md
4. rational_number.md
5. complex_number.md
6. prime_number.md
7. bug.md
8. off_by_one.md
9. normlization.md
10. probability.md
11. zero.md
12. zero.md
13. assembly.md