I have 15 column and I want Calc multiple all these and return answer to one cell. How can I multiple column ranges?
The function is product(range). If you want to values in the first row for columns A through E, then in your one cell type: =PRODUCT(A1:E1)
The range A1:E1 could span multiple rows (ex., A1:E5 multiplies all values in the 5x5 matrix). You can also specify more than one range, such as =product(A1:E1, H1:J1).