vlookup almost does this but not completely...

[newToExcel]

hey guys,

here's my problem
look at the 2 images attatched. one has 3 cols and other has 20.

the 3 cols image, can have the same # in multilple rows in the first col. wat i want to, depending on wat the # is in the col A of(2nd image), i want to sum up all the enteries on the 3rd col of (1st image).

i dunno if that makes sense so i'll try to give an example.

in the 2nd image, look at the box with red square, now look at the box above it. this # is the value that's gonna determine what i get from the table(1st image).

right now, the 1st col (1st image) has all 1's. so in this case, i want to sum up all the rows of 3rd col (1st image) and return the value to the highlited box(2nd image).

currently i'm using vlookup but i know that it doesnt sum up stuff

i have tried for 2 hrs to get this and have reached a dead end everytime.

I think i have seen a solution to this a while back somewhere, i just cant remember where.

any help would be greatly appreciated.