Mathematica Journal: One Liners

*To*: mathgroup at yoda.physics.unc.edu*Subject*: Mathematica Journal: One Liners*From*: ilan at leland.stanford.edu (ilan vardi)*Date*: Mon, 27 Apr 92 00:47:31 -0700*Cc*: wri-tech

In the new issue of the Mathematica Journal, One Liners, there is a program called DigitalRoots which gives the result of iterating the sum of the digits of an integer. The code given there was DigitalRoots[n_]:= FixedPoint[(Plus @@ IntegerDigits[#])&, n] I have discovered the following more efficient program to compute this: MyDigitalRoots[n_]:= Mod[n, 9] There was also a program to reverse the digits of a number: ReverseInteger[n_]:= Module[{m = IntegerDigits[n], i}, Table[10^i, {i, 0,Length[m]-1}], m] My program (which only takes One Line) is: MyReverseInteger[n_]:= Fold[#1 10 + #2&, 0, Reverse[IntegerDigits[n]]] -Ilan Vardi