https://communities.sas.com/t5/SAS-Programming/how-to-position-the-columns-in-the-same-observation/m-p/42147#M8658 in a data step I would define an array using the : (colon) suffix to include all the colXX variables and just accumulate the last 3 like<BR /> Array cols(*) col: ;<BR /> last3 = 0 ;<BR /> do idx = dim(cols) to dim(cols)-2;<BR /> last3+cols( idx);<BR /> end;<BR /> <BR /> Then no matter how many COLxx columns are present only the last 3 are summed Sun, 03 Apr 2011 02:22:40 GMT Peter_C 2011-04-03T02:22:40Z https://communities.sas.com/t5/SAS-Programming/how-to-position-the-columns-in-the-same-observation/m-p/42146#M8657 for instance:<BR /> <BR /> one of the observation from the datasets:<BR /> <BR /> total of 60 columns<BR /> col1 col2 col3 col4....col60.<BR /> <BR /> i would like to perform the calculations for the last three columns, such as col58 col59 col60. <BR /> <BR /> the total of the columns is changing. how can i calculate the total of col58..col60 Fri, 01 Apr 2011 05:28:04 GMT https://communities.sas.com/t5/SAS-Programming/how-to-position-the-columns-in-the-same-observation/m-p/42146#M8657 jdk123 2011-04-01T05:28:04Z https://communities.sas.com/t5/SAS-Programming/how-to-position-the-columns-in-the-same-observation/m-p/42147#M8658 in a data step I would define an array using the : (colon) suffix to include all the colXX variables and just accumulate the last 3 like<BR /> Array cols(*) col: ;<BR /> last3 = 0 ;<BR /> do idx = dim(cols) to dim(cols)-2;<BR /> last3+cols( idx);<BR /> end;<BR /> <BR /> Then no matter how many COLxx columns are present only the last 3 are summed Sun, 03 Apr 2011 02:22:40 GMT https://communities.sas.com/t5/SAS-Programming/how-to-position-the-columns-in-the-same-observation/m-p/42147#M8658 Peter_C 2011-04-03T02:22:40Z