Frequently Requested OS400 Commands

What are the most frequently used OS400 commands I can never remember?

How can I tell how much memory I have on this machine?
WRKDSYSSTS

How do I tell what my serial number is?
CONTAINED IN THE RACK CONFIG

How can I tell how much disk capacity I have ?
WRKDSKSTS

How can I tell what my disk utilization is?
WRKDSKSTS

How can I tell what OS400 version I have?
GO LICPGM OPT10

How do I get my software keys?
CALL THE KEY CENTER (800) 446-8989 EXT 1