Possible to "gray out" or not include a cell value until activated?

yes they can be excluded but use

Please Login or Register  to view this content.

that is sum all rows in a when the corresponding value in b is grater than 99. What is the off/on (trigger). could you spare a sample workbook ?

Hi and welcome to the forum

I think what you need to do with this is use a helper column to "x" those cells you dont want to include (lets assume you used B). You would then use =SUMIF($A$1:$A$100"",$B$1:$B$100)

See the attached. It gives you exactly what was suggested above by both rcm and myself (did you even try it??)

Also, I added Conditional Formatting to "grey out" those cells selected with the x

Based on your last post it seems that you are satisfied with the solution(s) you've received but you haven't marked your thread as SOLVED. If your problem has not been solved you can use Thread Tools (located above your first post) and choose "Mark this thread as unsolved".
Thanks.

Also, as a relatively new member of the forum, you may not be aware that you can thank those who have helped you by clicking the small star icon located in the lower left corner of the post in which the help was given. By doing so you can add to the reputation(s) of those who helped.

=SUMIF($A$1:$A$100"",$B$1:$B$100)

(did you even try it??)

A little miss typing
You missed a comma after $A$100 then it is not working.