LibreOffice 7.5 Help
SUM(Number 1 [; Number 2 [; … [; Number 255]]])
=SUM(2;3;4) returns 9.
=SUM(A1;A3;B5) calculates the sum of the three cells.
=SUM(A1:E10) calculates the sum of all cells in the A1 to E10 cell range.
A formula such as =SUM((A1:A40>=C1)*(A1:A40<C2)*B1:B40) may be entered as an array formula by pressing the Shift+Command+Ctrl+Enter keys instead of simply pressing the Enter key to finish entering the formula. The formula will then be shown in the Formula bar enclosed in braces and operates by multiplying corresponding elements of the arrays together and returning their sum.
Refer to the SUM wiki page for more details about this function.