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FromDigits

  • FromDigits[ list ] constructs an integer from the list of its decimal digits.
  • FromDigits[ list , b ] takes the digits to be given in base b.
  • Example: FromDigits[ 3,7,4 ].
  • FromDigits is effectively the inverse of IntegerDigits.
  • FromDigits[ list , n , b ] takes n to be an exponent, so that FromDigits can also be used as the inverse of RealDigits.
  • Since IntegerDigits[ n ] discards the sign of n, FromDigits[IntegerDigits[ n ]] is Abs[ n ] not just n.
  • The base b can be any expression, not necessarily a positive integer.
  • See the Mathematica book: Section 3.1.3.
  • See also: IntegerDigits, RealDigits, NumberForm.