The leader of the sixth grade messed up the 6 keys and 6 locks in each class. Please help to calculate how many times it takes at most to match them again.
六年级组长把各班6把钥匙和6把锁搞乱了，请你帮助算一算，最多要试多少次，可以重新配起来．
<gadget id="calculator">5 + 4 + 3 + 2 + 1</gadget>
<output>15</output>

<result>15</result>