Digit

The number of digits $D$ in an Integer $n$ is the number of numbers in some base (usually 10) required to represent it. The numbers 1 to 9 are therefore single digits, while the numbers 10 to 99 are double digits. Terms such as ``double-digit inflation'' are occasionally encountered, although this particular usage has thankfully not been needed in the U.S. for some time. The number of (base 10) digits in a number $n$ can be calculated as

$$D = \left\lfloor{1+\log_{10} \vert n\vert}\right\rfloor ,$$

where $\left\lfloor{x}\right\rfloor$ is the Floor Function.

See also 196-Algorithm, Additive Persistence, Digitaddition, Digital Root, Factorion, Figures, Length (Number), Multiplicative Persistence, Narcissistic Number, Scientific Notation, Significant Digits, Smith Number