@Jithan
Your description is unclear. I believe you are saying that with what appears to be 00:50 in A2 and what appears to be 00:40 in B2, =A2-B2 results in what appears to be 00:00 in C2, let's say. Right?
Look carefully at the cell formats. I suspect (*) that A2 and B2 are formatted as Custom m:ss or something similar, whereas C2 is formatted as Custom h:mm.
More to the point, the values in A2 and B2 are 0m 50s and 0m 40s. Thus, A2-B2 results in 0m 10s.
You can confirm by formatting C2 as Custom m:ss or h:mm:ss.
You can also use =SECOND(A2) and =SECOND(B2).
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(*) I should add that that is a wild guess on a potentially misunderstanding of the problem.
If my guess does not seem right, I suggest that you attach an example Excel file to a response here. Click the "browse" link near the bottom of the reply window.
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(**) If the forum does not allow you enter URLs, you can spell out the beginning part of the URL; for example, techcommunity dot microsoft dot /t5/excel/excel-time-difference-error/m-p/3575889 .
