Even easier is to use printf.

#! perl -slw
use strict;

my (@names, @numbers);

while (<DATA>) {
    chomp;
    my ($name, $number) = split' ';
    push @names, $name;
    push @numbers, $number
}
# right justified
printf "%10s : %8d\n", $names[$_], $numbers[$_] for 0 .. $#names;
print '';

# left justified
printf "%-10s : %-8d\n", $names[$_], $numbers[$_] for 0 .. $#names;
print '';

# strings left justified, numbers right justified
printf "%-10s : %8d\n", $names[$_], $numbers[$_] for 0 .. $#names;
print '';

__DATA__
nameone 101
nametwo 123456
namethree 1234567

C:\test>216893
   nameone :      101
   nametwo :   123456
 namethree :  1234567

nameone    : 101
nametwo    : 123456
namethree  : 1234567

nameone    :      101
nametwo    :   123456
namethree  :  1234567
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