First thing is, use strict; and use warnings;. There are syntax errors in the code you specified.

Here's one way to extract out the hash slice you need...

use warnings;
use strict;

my $household = {
    23 => { last => 'Smith', first => 'Mary' },
    22 => { last => 'Jones', first => 'Bob' },
};

my $name = join ' ', @{ $household->{23} }{'first', 'last'};
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-stevieb