(8) On a digital clock, nine is the greatest interval obtainable by advancing some sort of “snooze counter” on the ones column. But why mess with the ones column? Why not put the snooze counter on the tens column and advance that by one?

This wouldn’t work for every time.

If you set the alarm clock to 6:15 or 6:45, you would only get a 5 minute snooze time, if it were based on the 10s column.

Surely if it is 6.15 and you advance the counter of the tens column by one it will go to 6.25, giving you ten more minutes. You seem to be assuming that the ones column will be cleared, but why assume that?

No, I think he’s saying that if we put the snooze counter on the 10s, then it will go:
6:15
6:16
6:17
6:18
6:19
6:20 < tens changed, Alarm!

Which seems to be true. You could only get 10 minutes snooze if your alarm was set for a multiple of 10 to begin with, so it went:
6:10 < Alarm! blerghtooearly Snooze slam
6:11
6:12
6:13
6:14
6:15
6:16
6:17
6:18
6:19
6:20 < tens changed, Alarm!

I’m going with the number 8 answer as well. My alarm goes off the instant the numbers indicate the 9th minute, regardless of when in the first minute I hit the snooze button.

As you note, the algorithm can simply be “activate when the ones place is equal to (x+9) mod 10”. That doesn’t work for the tens place unless you compare two digits. Someone must have realized that you could save 12 microcents per unit with a 9-minute snooze.

I’m also not sure which engineer said “Nice try, bub, but clocks don’t count that way.” In fact, many digital clocks do use the number of AC cycles for timekeeping. Also, while it’s true that most clocks use BCD (binary coded decimal) instead of strict binary for display purposes, but that doesn’t mean an internal counter can’t be binary.

Welcome to the Straight Dope Message Boards, hotpepper67, we’re glad you found us. For future ref: when you start a thread, it’s helpful to other readers if you provide a link to the column in question. Saves search time, and helps keep us on the same page. No biggie, I’ve added the link for you, and you’ll know for next time, and, as I say, welcome!

I’d find that very useful, actually. I’m currently working as a substitute teacher. Every morning, I wake up earlier than I’d like, stagger over to my computer to check to see if I’m working today, and then either work myself into a frenzy to get ready, or stagger back to bed and go back to sleep for a while longer. It’s not for everyone, of course, but that’s why it’s a settable option.