Hi
I have a list of 4 suppliers for a business i would to everytime one certain supply is selected and the invoice total is entered for it to add them together and give me a total for a month on a separate sheet is this possible? E.g. If I select Microsoft on my drop down menuand enter 110 pound as a invoice total when I enter it again in week 2-5 with different invoice totals I would like it to be able to give me a total relating to the selecting supplier rather than the amount hope you understand this

Thank in advance
:)