<?php

echo '<form method="post">
1 Is Equal By <input type="text" value="" name="number" size="10" />
<input type="submit" value="submit" name="submit"/></form>';

if (isset($_POST['submit'])) {

if (isset($_POST['number'])) {
$number=$_POST['number'];
} else {
echo "No number specified!";
}
if (isset($number)) {
if ($number=='1') {
    echo 'Yes, '.$number.' is equal to 1!';
} else {
    echo 'Not, '.$number.' is not equal to 1!';
}
}
}
?>