# alarm clock snooze 9 minutes?

**URL:** <https://boards.straightdope.com/t/alarm-clock-snooze-9-minutes/222945>\
**Category:** Factual Questions\
**Created:** [January 6, 2004, 3:05am UTC](https://boards.straightdope.com/t/alarm-clock-snooze-9-minutes/222945 "2004-01-06T03:05:46Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Zaphod7](https://avatars.discourse-cdn.com/v4/letter/z/df788c/32.png) [@Zaphod7](https://boards.straightdope.com/u/Zaphod7)\
**Post date:** [January 6, 2004, 3:05am UTC](https://boards.straightdope.com/t/alarm-clock-snooze-9-minutes/222945/1 "2004-01-06T03:05:46Z")

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Why are alarm clock snooze on a 9 minute rotation?

i know it takes most people on average 7 minutes to fall asleep, so why 9 minutes for an alarm.  
I mean i know i live in a very IT world where things need to be rounded nicely, but 10 just seems so much nicer than 9, it just seems like such an odd number of minutes but there must be a reason behind it.

Zaphod

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**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\
**Post date:** [January 6, 2004, 3:09am UTC](https://boards.straightdope.com/t/alarm-clock-snooze-9-minutes/222945/2 "2004-01-06T03:09:53Z")

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[Cecil speaks.](http://www.straightdope.com/classics/a991126.html)

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<div class="post-metadata">

**Author:** ![Zaphod7](https://avatars.discourse-cdn.com/v4/letter/z/df788c/32.png) [@Zaphod7](https://boards.straightdope.com/u/Zaphod7)\
**Post date:** [January 6, 2004, 3:13am UTC](https://boards.straightdope.com/t/alarm-clock-snooze-9-minutes/222945/3 "2004-01-06T03:13:15Z")

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sweet loads of speculation but it seems like a foggy subject, i guess we will just never know for sure.

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**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\
**Post date:** [January 6, 2004, 3:59am UTC](https://boards.straightdope.com/t/alarm-clock-snooze-9-minutes/222945/4 "2004-01-06T03:59:50Z")

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There was a discussion at the Cecil’s Columns forum, which seemed to come to a conclusion closest to Cecil’s reason #8:

> [@](#):
>
> (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?

What Cecil didn’t realize when he wrote this is that the first clocks had precious little program memory to work with, and a reasonable guess is that the alarm was set to un-snooze when the ones minutes digit was equal to one less than the current minute. In other words, if the current time is 6:45:12 when you hit the snooze button, the feeble logic puts the number “4” in its memory, and as soon as the ones digit matches (this will be at 6:54), the alarm will go off again. This algorithm would be extremely easy to implement in a small amount of code and scratchpad memory.

Why do they do it now, when a transistor costs 0.000005 cents? My guess is that the logic works and no one wants to take the trouble to mess with it.