Automatic Cell Entry from One Column to Another

[LabraLime]

Hello!
I have a list of 41 different document numbers that get entered into a larger set. I'm trying to see how I can create a formula that will automatically enter an "x" into a specific column if any of the 41 are triggered in a separate column. Any suggestions?

For example:
I have a list of document numbers that need to be checked with an "x" (for this ex: 123, 134, 333)-I want the "x" to automatically populate into a separate column so that the whole sheet can be easily filtered by that "x" column.

Doc #	other unrelated data	Need to be checked [x]
123​	aaa	x
122​	aaa
134​	aaa	x
333​	aaa	x

 

[Joe4]

You are welcome!
Glad I was able to help.