|I assume that you mean that the second list only contains CAS numbers that have a change associated with them. If that's the case, then you could use a Conditional Formatting Rule as follows:|
Let's say your main list of CSA numbers is in Column A and the list of CSA numbers with changes associated with them is in Column B.
Select Column A and use this CF Rule:
This will use VLOOKUP to find the numbers from Column A in Column B. If the number exists, the NOT(ISNA(... portion will return TRUE and the cell will take on the CF format that you chose.
Note, the CSA numbers must be the only things in the cells and must match exactly.
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