Time intervals SUM unexpected result

Hi all,

I have this sheet where I calculate the daily time worked based on the sum of time intervals and then calculate the time effectively worked against an expected time value. Based on the final result I present, through conditional formatting, the difference in bold red if time worked was less than the expected, black normal if they're equal and bold black if time worked is greater.

For instance:
[Morning time equals the sum of up to 2 intervals)]
N1 = (C1-B1)+(E1-D1)

[Afternoon time equals the sum of up to 4 intervals]
O1 = (G1-F1)+(I1-H1)+(K1-J1)+(M1-L1)

Daily time equals the sum of morning time and afternoon time
P1 = N1+O1

Expected time
Q1

Difference between worked time and expected time
P1-Q1

The problem is that when "apparently" the time worked is equal to the expected time and the subtraction of the 2 shows ZERO, the SIGN function doesn't return ZERO as expected.

First I thought the problem was with the SIGN function so I replaced P1 result with a literal value equal to Q1 and the result of the SIGN function was zero as expected. No problem here.

So the problem must be in the sum of the periods of time. Apparently although:
-the result of the sum shows the same value as Q1 and
-the subtraction of the 2 returns ZERO and
- if I test one value against the other it returns TRUE
they are not exactly the same.

All cells are formatted as "Time" of type "13:30".

I'm running out out of ideas as what can be the origin of this difference. Although I'm not giving up on solving it myself, I have to admit that some help would be appreciated.

Thanks on advance,
ND

Here goes.

Morning worked time
(12:50-9:35) = 3:15
Afternoon worked time
(18:45-14:00) = 4:45
Daily worked time
3:15+4:45 = 8:00
Expected work time
8:00
Difference between worked and expected time
8:00-8:00 = 0

If I use the SIGN function on the subtraction, I get -1 instead of the expected 0
SIGN(8:00-8:00) = -1

If time is less than zero it is not displayed.

So I use ABS function to show both negative and positive time values and the SIGN function to determine the formatting. Bold Red if "-1", Bold black if "1".

Here goes an example workbook (I hope)

Thank you Pepe Le Mokko.
Thank you Spencer101.

You were right Pepe. It had to do with the floating point. I rounded the values before the subtraction and it solved the problem (so it seems).

Spencer, I tried your sugestion and it worked fine in the example I posted but it didn't work on the real sheet. The formula there is a bit more complex because it takes extra stuff in to consideration.

Thank u both for the quick replies.

Hope I can return the favour in the future.