c:\@Work\Perl\monks>perl -wMstrict -le
"my $x = '1 2 3kg 4 5 6 7 8 9 10Kg 11 12 13 kg 14 15';
 print qq{string \$x: '$x'};
 ;;
 printf qq{captured '$1'  } while $x =~ /\G(\d+)\s*kg\s*/ig;
 print '----------';
"
string $x: '1 2 3kg 4 5 6 7 8 9 10Kg 11 12 13 kg 14 15'
----------