Trying to sum three mulitplied cell pairs (A17*A8,
A20*A21, AND A23*A24), then, multiply that sum by a final
cell value (A34). Problem is, A17, A20, and A23 are
linked to cells in another sheet where the formula is =IF
(B10="","",SUM(AB10:AB13)) - which returns a #Value! error
because of the quotes "" (when the value is blank). Can't
use a zero instead of the quotes, so I'm advised to
substitute function calls, the "Ns", in the below
formula. Can someone help me further - how to set this
up.

"Add some function calls to convert the null string to
zero":
=SUM(((A17*A18)+(N(A20)*N(A21))+(N(A23)*N(A24)))*A 34)

Thanks, Phl