Solution to mensa puzzle 51

51.php

<?php

$answer = 11;

while (!check($answer)) {
    echo "{$answer} is not correct.";
    $answer += 11;
    echo " trying {$answer}...\n";
}

echo "answer is {$answer}\n";


function check($answer)
{
    $conditions = array(
        ($answer % 3 == 2),
        ($answer % 5 == 4),
        ($answer % 7 == 6),
        ($answer % 9 == 8),
        ($answer % 11 == 0),
    );

    var_dump($conditions);
    foreach ($conditions as $condition) {
        if (!$condition) {
            return false;
        }
    }
    return true;
}

Any idea how to figure this out manually, faster than writing a script?

This is a good brute force way. Can you write it to be more efficient?