Combine various cells in to one array

[Odin]

I have the following formula that I would like to shorten it. Is it
possible?

=12.5%*(($A$1=$C1)+(($A$1=$C6)*2)+(($A$1=$C11)*3)+(($A$1=$C16)*4)+(($A$1=$C21)*5))

To following is just an idea but doesn't work on excel.

=12.5%*(($C1,$C6,$C11,$C16,$C21)=$A$1)*{1,2,3,4,5}

I wanted to use SUMPRODUCT but it only take contiguous array. Thanks
for any input.

PS: I can not use array C1:C21 because other cells within it may equal
to $A$1 which will return incorrect result. And the 3rd part, {1,2...}
would be too long.

 

[Lars-Åke Aspelin]

I have the following formula that I would like to shorten it. Is it
possible?

=12.5%*(($A$1=$C1)+(($A$1=$C6)*2)+(($A$1=$C11)*3)+(($A$1=$C16)*4)+(($A$1=$C21)*5))

To following is just an idea but doesn't work on excel.

=12.5%*(($C1,$C6,$C11,$C16,$C21)=$A$1)*{1,2,3,4,5}

I wanted to use SUMPRODUCT but it only take contiguous array. Thanks
for any input.

PS: I can not use array C1:C21 because other cells within it may equal
to $A$1 which will return incorrect result. And the 3rd part, {1,2...}
would be too long.

Try this formula, it is 19 characters shorter than the one you have:

=12.5%*SUMPRODUCT((MOD(ROW(5:25),5)=0)*ROW(5:25)/5*(C1:C21=A1))

Hope this helps / Lars-Åke