Please consider using for loops to simplify your array assignment logic to reduce the possibility of mistakes. pp() is very useful for checking that everything has worked as expected.

use feature ":5.14";
use warnings FATAL => qw(all);
use strict;
use Data::Dump qw(dump pp);

my $wheel = 2100; 
my @chwhs = qw (23 26  27);                  # test data
my @cogs  = qw (11 13 15 17 19 21 24 28 32); # test data

my $gear;

for my $c(0..2)
 {$gear->[$c][$_] = $wheel*$chwhs[$c]/$cogs[$_] for 0..8;
 }

pp($gear);
[download]

Produces

[
  [
    "4390.90909090909",
    "3715.38461538462",
    3220,
    "2841.17647058824",
    "2542.10526315789",
    2300,
    "2012.5",
    1725,
    "1509.375",
  ],
  [
    "4963.63636363636",
    4200,
    3640,
    "3211.76470588235",
    "2873.68421052632",
    2600,
    2275,
    1950,
    "1706.25",
  ],
  [
    "5154.54545454546",
    "4361.53846153846",
    3780,
    "3335.29411764706",
    "2984.21052631579",
    2700,
    "2362.5",
    2025,
    "1771.875",
  ],
]
[download]