Sort of. Instead of mnemonics, I find it easier to remember when I know how a concept is derived from basic principles. So, first we observe that 1am and 1:00 in 24h format are the same time. Then, we consider the hour before that. That hour is 0 in 24h format. It also belongs to the same day. Since the day is split in two equal halves by AM/PM, then hour 0 in 24h format is hour X am, where X is the hour before 1 am. That is hour 12. Therefore, 12am is 0 o'clock.
The other fact that helps me remember is that 12 hour clocks were invented before the number 0, and afterwards 24h clocks are 0-based, so 12 on an old clock is the start of the am or pm cycle respectively because there is no 0. Really 12 should be 0 and then it all makes sense.
The other fact that helps me remember is that 12 hour clocks were invented before the number 0, and afterwards 24h clocks are 0-based, so 12 on an old clock is the start of the am or pm cycle respectively because there is no 0. Really 12 should be 0 and then it all makes sense.