calculation for certain columns

[Mohd]

Hi
I want the functions that make this option:

first it should check if the columns A3:A10 has these letters "IS","IT" at
beggining, then sum the values in E3:E10 THEN devide it by sum of values in
D310 for all achiving A3:A10 columns criteria

 

[Ragdyer]

One way ... assuming "IS" *OR* "IT":

=SUMPRODUCT((LEFT(A3:A10,2)={"IS","IT"})*E3:E10)/SUMPRODUCT((LEFT(A3:A10,2)=
{"IS","IT"})*D310)