They are not being sent from your html page probably. You can assign defaults like this;

my $name   = $q->param('name')   || 'noname';
my $day    = $q->param('day')    || 'noday';
my $number = $q->param('number') || 'nonumber';
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The elements after the print line should be comma separated and you shouldn't be printing after the end_html

print $q->header,
$q->start_html( -title => "Add user", -bgcolor => "#ffffff"),
$q->p("Data submitted"),
$q->tt("$name<br/>$day<br/>$number"),
$q->end_html;
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And you may wish to add this while developing to see any errors in the browser.