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added 24 characters in body

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edited Oct 27, 2016 at 17:27

Perl 3334 28 bytes

Includes +1 for -p

$_=eval join"+"s/./+$&/g,split''$_=eval while/../

Uses the method described in the question.

Example:

$ echo -n 495106 | perl -p DigitalRoot.pl
7

$_=eval join"+",split'' while/../

Uses the method described in the question.

Example:

$ echo -n 495106 | perl -p DigitalRoot.pl
7

Includes +1 for -p

s/./+$&/g,$_=eval while/../

Uses the method described in the question.

Example:

$ echo -n 495106 | perl -p DigitalRoot.pl
7

Source Link

created Oct 27, 2016 at 14:25

$_=eval join"+",split'' while/../

Uses the method described in the question.

Example:

$ echo -n 495106 | perl -p DigitalRoot.pl
7