How should I add an ID variable

[superbug]

I have a large dataset. I want to add an ID variable in the data.  For every 250 rows, I want them to have the same ID. that is, for the first 250 rows, I want ID=1; the next 250 rows, I want ID=2; then then next 250 rows, ID=3; etc. 

What's the efficient SAS code to help me do that?

Thanks! 

[novinosrin · Accepted solution]

data want;
 set have curobs=n;
 if mod(n,250)=1 then id+1;
run;

[superbug]

@novinosrin 

Thanks much!

You are always so helpful!