digit
[C] Countable
pl: digits
The term carries a clinical precision when used in anatomy, stripping away the common labels of finger or toe to treat them as interchangeable units of a series. It is rarely used in casual conversation unless the speaker is a doctor or a scientist, as it feels sterile and technical. In mathematics and computing, the word evokes the concept of a building block. It represents the smallest discrete unit of a number system, creating a mental image of a single slot or a single switch in a binary sequence, which differentiates it from the total value of a number.
Countable when referring to individual numbers (a 5-digit zip code) or specific fingers and toes (the digit of the hand).