Sum excluding n/a's

A B
#N/A 4
12 9
4 8
#N/A 6


Want to multiply these columns together but to exclude the #N/A, or if it is there, to return result as 0. Any ideas?

for a single cell
=IF(ISERROR(A1*B1),0,A1*B1)

for a range, entered as an array, so with shift ctrl enter instead of enter at the end

=SUM(IF(ISERROR(A1:A9*B1:B9),0,A1:A9*B1:B9))

Regards

Dav

Great. Thanks both for your help.