gives a list of the digits in the approximate real number x, together with the number of digits that are to the left of the decimal point.

RealDigits[x, b]
gives a list of base-b digits in x.

RealDigits[x, b, len]
gives a list of len digits.

RealDigits[x, b, len, n]
gives len digits starting with the coefficient of .


  • RealDigits gives the most significant digits first, as in standard positional notation.
  • RealDigits[x] normally returns a list of digits of length Round[Precision[x]].
  • RealDigits[x] and RealDigits[x, b] normally require that x be an approximate real number, returned for example by N. RealDigits[x, b, len] also works on exact numbers.
  • For integers and rational numbers with terminating digit expansions, RealDigits[x] returns an ordinary list of digits. For rational numbers with non-terminating digit expansions, it yields a list of the form representing the digit sequence consisting of the followed by infinite cyclic repetitions of the . »
  • If len is larger than Precision[x]/Log[10, b], then remaining digits are filled in as Indeterminate.
  • RealDigits[x, b, len, n] starts with the digit which is the coefficient of , truncating or padding with zeros as necessary. »
  • RealDigits[x, b, len, -1] starts with the digit immediately to the right of the base-b decimal point in x.
  • RealDigits[x, b, Automatic, n] gives as many digits as it can in a fixed-precision number.
  • The base b in RealDigits[x, b] need not be an integer. For any real b such that b>1, RealDigits[x, b] successively finds the largest integer multiples of powers of b that can be removed while leaving a non-negative remainder.
  • RealDigits[x] discards the sign of x.
  • RealDigits[0.] gives {{0}, -Floor[Accuracy[0.]]}.
  • FromDigits can be used as the inverse of RealDigits.
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