Trying to combine an IF statement and an OR statement and NOT(ISBLANK)

edited 12/09/19 in Smartsheet Basics

I am trying to utilize an IF statement and an OR statement. I am able to successfully make each statement work independently but when I put them together it doesn't work for me.  I am hoping someone can look at each of my statements and see what I am missing.  I think I am on the right track but I keep on getting an Error message with each variation. I will also include my examples:

1# =IF([1 - ROM Requirements (Status)]4 = "Completed", "100%") This works correctly.

2# =IF(NOT(ISBLANK([1 - ROM Requirements (Completed Date)]1)), "100%") This works correctly.

3# =IF([1 - ROM Requirements (Status)]2 = "Completed", "100%", OR(NOT(ISBLANK([1 - ROM Requirements (Completed Date)]2, "100%", 0)))  This was my attempt at combining them but it only works partially.

I have tried so many variations that I have lost count and can't remember what I have tried.  If someone can help get me on the right track again that would be great.