Using variables in functions

[Natan]

I want to use the sum function to sum different values of
a range. eg. if the range = a1:a20 i want to use =sum
(a1:?)where ? refers to a cell or formula where i can
change the value. If I change the value to say 5 it must
sum a1 to a5, or if i change it to 10 it must sum a1 to
a10. Thanks

 

[JE McGimpsey]

One way:

Assume your ? is in cell B1:

=SUM(OFFSET(A1,0,0,B1,1))