If is always 1,2,3....N you can use Gauss's solution

=IF(ISEVEN(A1),(A1/2)*(1+A1),INT(A1/2)*(A1)+A1)

where A1 holds N

otherwise use

=SUMPRODUCT(--(ROW(INDIRECT(A1&":"&A2))))

where A1 and A2 are first and last numbers


--
HTH

Bob Phillips

"LAdekoya" wrote in message
...
I am looking for a formula to which I can supply a number N and have it
calculate 1+2+3+4.....+N. I realise that I can enter 1 to N in as many
cells
then use SUM but this won't do for what I need to achieve.