Kostis: Excellent formula. I think, however you have inverted what the
OP was looking for, and that this may be what they need:

=IF(B2="ENABLE DEVICE", A2-MAX(($A$2:A2)*IF($B$2:B2="MALF DEVICE", 1,
0)), "")

Array entered with Ctrl+Shift+Enter and then copied down the range of
20,000+ rows.

Again, format the output cells (C2:C??) as Customdd:hh:mm:ss (use the
'dd:' option if you anticipate gaps of 24 hours or more.

Good Luck and thanks again Kostis.


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swatsp0p


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