I have two values: like A= 783 and B = 16272 seconds[.] I want to calculate number of A in per seconds like (783/16272) a/seconds. So I use (A/B). but the result shows= 01:09:18.
Why are you formatting the result as [h]:mm:ss?
That calculates unit of A per second. The unit of measure is the same as the unit of A. Presumably, that is not time squared. Right?
Do you really want to calculate seconds per unit of A?
If so, ostenibly the calculation should =B1/A1 formatted as General or Number.
But if you want the result to be formatted as [h]:mm:ss, the calculation should be:
=B1/A1/86400
to convert decimal seconds into Excel time, which is suitable for that format.