Hello. I'm practicing because it's a test in December. Sadly I don't understand exercise number 2. Please explain why there are 117 columns. I keep getting 25. (Just in case, I ran the answer as it is, but it still comes out as 25.) ----------------------------------------------------------------------------------- Answer: 117 proc sort data=cert.input08a out=work.input08a;   by ID; run; proc sort data=cert.input08b out=work.input08b;   by ID; run; data results.match08 results.nomatch08 (drop=ex: );   merge work.input08a (in=a) work.input08b (in=b);   by ID;   if a and b then output results.match08;   else output results.nomatch08; run; proc contents data=results.match08; run; proc contents data=results.nomatch08; run; ... View more