What does a colon do in MS Excel?

I've used MS Excel for a long time, but I encountered something new the other day. I was trying to enter the contrast ratio for an LCD screen into a cell in my Excel spreadsheet. The contrast ratio was 700:1. But as soon as I entered "700:1 ", Excel converted it to "29.17 ". I assumed that Excel would NOT convert 700:1 and leave my entry as a character string because the ":" is not a numeric digit or an arithmetic operation and I did not have an "=" sign at the beginning of the string. But that's not what happened.

Of course, I could put a double or single quote at the beginning of the string, and then "700:1 or '700:1 would remain in the spreadsheet cell. Also, I realize that the ":" operator is a range indicator, but I was not entering a cell location, just two numbers. So what was Excel doing with what I entered, and why did it convert 700:1 into 29.17 ?

Thanks for any comments on this minor but annoying problem.

 

Thanks to all who responded. I guess it's still a mystery as to what Excel actually does to change "700:1" into 29.17. If anybody else has any ideas, I would still be interested. Thanks again !!

 

Thanks, Arie, I finally understand !!

700:1 is interpreted by Excel as a TIME and converts it to

700 hours and 1 minute.

700 hours divided by 24 hours/day = 29.17 days so that's where the 29.17 comes from.

Thanks !!