There are more than one way to do this.

#!/usr/bin/perl

use strict;

my %hash = ( 4 =>  [10, "mango"] ,
             2 =>  [04, "banana"] ,
             3 =>  [20, "apple"],
           );

for my $i ( keys %hash ) {
    print "$i: $hash{$i}->[0]\n";
}
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