A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
If your formulas use a comma for a list separator character try,
=SUM(K11 * L11, M11)
=SUM(PRODUCT(K11:L11), M11)
'simpler as,
=K11*L11+M11 'mathematical hierarchy rules apply
If your computer uses a semi-colon then,
=SUM(K11 * L11; M11)
=SUM(PRODUCT(K11:L11); M11)