"0123456789" =~ /(\d{3})/g;

##</code><code>##

main::(-e:1):   1
  DB<1> $foo = "123456790"

  DB<2> @w1 = ( $foo =~ /(\d{3})/g );

  DB<3> x @w1
0  123
1  456
2  790

##</code><code>##

"0123456789" =~ /(?:(\d{3}))/g;

##</code><code>##

  DB<4> @w2 = ( $foo =~ /(?:(\d{3}))/g );

  DB<5> x @w2
0  123
1  456
2  790