I see that in your solution, you have an = sign in the middle of the
formula which i think is wrong. Do you understand where I am getting
with this.

To explain it to you again, I have to write this formula in cell E2:

=(E2*I$2)+(E25*I$3)+(E24*I$4)+(E23*I$5)+(E22*I$6)+ (E21*I$7)+(E20*I$8)+
(E19*I$9)+(E18*I$10)+(E17*I$11)+(E16*I$12)+(E15*I$ 13)+(E14*I$14)+(E13*I
$15)+(E12*I$16)+(E11*I$17)+(E10*I$18)+(E9*I$19)+(E 8*I$20)+(E7*I$21)+
(E6*I$22)+(E5*I$23)+(E4*I$24)+(E3*I$25)

In cell E3, I have to write this formula:

=(E3*I$2)+(E2*I$3)+(E25*I$4)+(E24*I$5)+(E23*I$6)+( E22*I$7)+(E21*I$8)+
(E20*I$9)+(E19*I$10)+(E18*I$11)+(E17*I$12)+(E16*I$ 13)+(E15*I$14)+(E14*I
$15)+(E13*I$16)+(E12*I$17)+(E11*I$18)+(E10*I$19)+( E9*I$20)+(E8*I$21)+
(E7*I$22)+(E6*I$23)+(E5*I$24)+(E4*I$25)

In cell E4, I have to write this formula:

=(E3*I$2)+(E2*I$3)+(E25*I$4)+(E24*I$5)+(E23*I$6)+( E22*I$7)+(E21*I$8)+
(E20*I$9)+(E19*I$10)+(E18*I$11)+(E17*I$12)+(E16*I$ 13)+(E15*I$14)+(E14*I
$15)+(E13*I$16)+(E12*I$17)+(E11*I$18)+(E10*I$19)+( E9*I$20)+(E8*I$21)+
(E7*I$22)+(E6*I$23)+(E5*I$24)+(E4*I$25)

I have to do this for 30 cells and it is a real pain to write lengthy
formula again and again. If you can understand the pattern from the
above, you should be able to suggest me some quick way out of this
pain. Thanks for your help