use strict;
use warnings;

my $string = "12 word 100,000 word 20,300 word word 180";

my @array = split /\s+/, $string;  # Perform your split.

$_ =~ tr/,//d for @array;          # Tidy up, removing commas.

$array[2] /= 10;                   # Do some math as a test.
print "$array[2]\n";               # Print the results of the
                                   # math which we just performed
                                   # on a value which had previously
                                   # been a string.