I need to be able to filter my data by serial number and return the total
quantity, then multiply by a constant number.

This is the formula I have thus far, but I don't know how to subtotal it...

=SUMIF(C1:C53,E55,F1:F53)*(0.085)

METER PRIOR CURRENT QTY SERIAL NO.
BLACK 95 2125 2030 KNF11183 IRC 3170
COLOR 144 2072 1928 KNF11183 IRC 3170
BLACK 227 382 155 KNF11467 IRC 3170
COLOR 69 423 354 KNF11467 IRC 3170
BLACK 63 1350 1287 KNF11474 IRC 3170
COLOR 34 942 908 KNF11474 IRC 3170

Any assistance would be appreciated!