Excel Formula. How to write formula in excel?

In Excel, cells are referred to by columns and rows...the columns (across) are A,B,C,D.....etc and the rows (down) 1,2,3,4...etc so the first cell on the sheet top left hand corner is A1 the next along B1 etc. To view the column letters and row numbers click on View and tick the Headings box

All formulae use this format so we need to know what cells you are trying to sum, I don't understand which ones you are referring to with your strange numbers. Please give more details

EDIT

You cant do that, you can only 'sum' numbers.

Because you have g/z in the same cell and also your number contains a '/'

- e.g A1 contains 'g/z 253/1'

you cant 'sum' this with anything, Excel doesn't understand the letters or the '/' character in the 'sum' equation.

I don't know what the spreadsheet is for, but you will have to find a new way to set it out.

Are the numbers to the right of the / character always one digit in length? If so, paste this formula in D16

=SUMPRODUCT((N(RIGHT(A1:A1000, 1)=RIGHT(D15,1)))*(B1:B1000))

If your data goes past row 1000, change the 1000's to some number larger than what you have. The above formula assumes all your data in column A starts with g/z.