Fill in a specific cell if meets criteria, based on data from another cell

[Luqman]

Hi All

Sequence	Units
23	0
24	0
16	0
27	0
18	0
14	0
17	0
12	3739.516
4	40130.15
11	1265.737
10	1562.042
3	49790.54
1	-33425.7
7	-870.226

How do i write a formula in such a way that 
If Sequence in ('17, '18', '27')

and (other criterias)

then 

Units = Units(from sequence '3' specifically) * 80%

[cjaneczko]

What is your Other Criteria? If Sequence isn't a String, don't use the quotes. If it is a string, the quotes are needed. So far what you have written down seems ok. You will need an ENDIF at the end of the statement, otherwise it looks fine as you have it typed up.

If you only want to multiply by the Unit value where Sequence = 3 then you should filter on Sequence = 3 and append that value to your main set of data. Then use the IF statement to multiply by the appended field.

[Qiu]

@Luqman 
I share the same question with @cjaneczko 
Can your further clarify and maybe share a desired output?

[CoG]

If multiple [Sequence] associations exist, you could also create a dependency table, that is then joined to your main table (or Find and Replaced) (to get the Units value) and then joined back to the main table again for the purpose of calculations (this would also remove the sequence check from the formula, but would necessitate you be careful to avoid cyclical references, which may cause abnormal outputs)

Sequence	Dependency
17	3
18	3
27	3
...	...

Your formula would then look something like

IF (other criteria) THEN [Units] = [Dependency_Units] * 80% ELSE [Units] ENDIF

More info, would be very helpful to tailor assistance, but I figured I may as well jump in and take a shot in the dark.