60 sec. = 1 min., 60 min. = 1 hr., 24 hr. = 1 day. The 60's came from ancient Babylonian number system. Where did the 24 come from?

Without supporting or refuting any of your assertions, it seems to me, that 24 is determined by all the other numbers. Otherwise, it wouldn't add up to a day, would it? If you start with 60 seconds, and 60 minutes, you get a time unit of one hour. There happen to be 24 of those in a day.

This assumes that the length of a second is fixed. If it were twice as long there would be only twelve hours in a day.

Our 24-hour day comes from the ancient Egyptians who divided day-time into 10 hours they measured with devices such as shadow clocks, and added a twilight hour at the beginning and another one at the end of the day-time.

It's not where did the 24 come from. It was 2 twelve hour parts to each day & the 12 came from the ancient Babylonian system.

That's what I was going to say. Of course, the numbers are arbitrary. A "day" is the time it takes the earth to rotate once. That time could be divided into 17 hours. Every third hour could be divided into 29 minutes with the remaining two divided into 91 minutes each. (And clocks would be much harder to build.)

Several replies seem to assume that the ancients set the definitions of second, minute, hour, based on the length of a second. I believe that the number of hours per day was first set to be 24 and the minutes and seconds were defined using 60. Notice that a similar thing was done for circles. The degree was defined to be 1/360 part of a circle (360 day calendar ?) and minutes and seconds defined using 60.

Maybe, start with base 6 start with 331 equal sized disks(pennies will do) place one on your desk around it place a tightly packed ring of the disks, (there will be six disks in that ring) then a second ring around the first ring(there will be 12 disks in the 2nd ring) then a 3rd ring (18 disks) then a 4th ring (24 disks) then a 5th ring (30 disks) it becomes that the number of the ring times 6 gives the number of disks in the ring etc... on up to the 10th ring(60 disks) and here we have multiplication and division then the disks in ring one multiplied by the disks in ring ten give us 360 fascinating in the potentials within it's simplicity care to discuss prime numbers in base 6? oops then 24 hours in a day sorry that seems to be beyond my ken

Unless we come up with something better: dywyddyr's nick lomb link/quote seems likely for the egyptians' approximate 10-,1 and 1,-12 = 24 hour day and a night Have you ever tried to tell time via a sun dial? The greeks, then seem to have pushed accuracy a tad farther. the egyptians also had a 360 day year, followed by 5 or 6 god/feast days tying in minutes and seconds probably followed development of modern chronometers mathman, are you looking for absolutes where only approximations and guesses from archaeological evidence can be found?

I am trying to get some idea (archeological or other evidence) how the number 12 was decided upon as the number of divisions for a half day. http://www.abc.net.au/science/articles/2011/11/15/3364432.htm as referenced Dywyddyr seems to be the answer. .

The thing with archaeology is that we only know today's results. For example the dig at Göbekli Tepe turned the whole agricultural revolution on it's head. It had been assumed for over 70 years that first there would be agriculture followed by complex hierarchical societies, and then monumental architecture. Now, the envelope has been pushed back several thousand years for the monumental architecture. If the knowing is derived from archaeology, then take the knowledge as "today's knowledge" only(not an absolute). Who knows what tomorrow might bring? One fine day, another archaeologist may uncover a sundial with divisions of 12 hours that predates Göbekli Tepe. It is also claimed that the egyptians divided the night into 18 forty minute segments which would add up to the 12 hours. ............ thanks for the curiosity