Harish wrote...
I have a formula in one cell and this is the tricky part: When I
copy the formulas to other rows in the same column, I want the
numbers to decrease instead of increase. For example, I have the
following formula in one cell

[reformatted and deleting unnecessary parentheses]
=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
+E8*I$20+E7*I$21+E6*I$22+E5*I$23+E4*I$24+E3*I$2 5
....

If you were entering this formula in cell X99, you could use the
following array formula instead.

=SUM(MMULT(--(MOD(ROW(E$2:E$25)+TRANSPOSE(ROW(E$2:E$25))-2*MIN(ROW(E
$2:E$25)),
ROWS(E$2:E$25))=ROWS(X$99:X99)-1),E$2:E$25)*$I$2:$I$25)

When you copy it down into X100, the X100 formula will return the same
result as

[reformatted and deleting unnecessary parentheses]
=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+I$25*E 4

Simplified matrix multiplication example.

/ 0 1 0 0 0 0 \ / a \ / b \
| 1 0 0 0 0 0 | | b | | a |
| 0 0 0 0 0 1 | | c | | f |
| 0 0 0 0 1 0 | * | d | = | e |
| 0 0 0 1 0 0 | | e | | d |
\ 0 0 1 0 0 0 / \ f / \ c /