Counting unique values from data on TWO separate excel tabs

Attached does this.

I had to create helper columns to do this. in the first tab i've joined A B C and D columns together as one string. In the next column I can check each row to see if the string exists in the previous rows. If yes then it is left blank, if not it joins A B and C together (ABC together will be used later). Then in Tab 2 i've done the same again but the fomula first checks tab 1 then tab 2 to decide if this row is a unique occurence.

Then you can use a formula to count the number of times A B anc C joined together occur (ie. IA BB 2013 is searched for in Col F but joined together to become IABB2013) in the same in tab 2 and add these together to get your result.

Hope that made sense!

Hello,

Check if the attached file is what you are expecting.

I literally made 3 array formula for each case: counting unique in tab 1, counting unique in tab 2, sum them together then minus the duplicated in both tab. There is no helper column.