Hi, Here is the code I have following code for N1 variable in the sample dataset below: proc sort data=dat.TestData out= test1; by trt; data test2; set test1; N1 + 1; by trt; if first.trt then N1 = 1; run;   I need to add N2 variable. It's a sequential number with same value for first 12 records within a TRT group: ID TRT N1 N2 101_017200024 TRT-A 1 1 101_330700016 TRT-A 2 1 102_0235003133 TRT-B 1 2 102_0235009018 TRT-B 2 2 102_0240009014 TRT-B 3 2 102_0240009014 TRT-B 4 2 102_0301006034 TRT-B 5 2 102_0301006034 TRT-B 6 2 102_0800009074 TRT-B 7 2 102_0805003099 TRT-B 8 2 102_0808009078 TRT-B 9 2 102_1302003096 TRT-B 10 2 103_010500013 TRT-B 11 2 103_011100001 TRT-B 12 2 103_011400013 TRT-B 13 3 103_011500002 TRT-B 14 3 103_011500002 TRT-B 15 3 103_011500015 TRT-B 16 3 103_011700008 TRT-B 17 3 103_011900013 TRT-B 18 3 103_011900020 TRT-B 19 3 103_012200004 TRT-C 1 4 103_012200005 TRT-C 2 4 103_012400003 TRT-C 3 4 103_012700022 TRT-C 4 4 103_012700022 TRT-C 5 4   Thank you! ... View more