One reason for using an array is to reduce the number of statements required to process variables. For example, in the DATA step below, the values of seven data set variables are converted from Fahrenheit to Celsius temperatures. data work.report; set master.temps; mon=5*(mon-32)/9; tue=5*(tue-32)/9; wed=5*(wed-32)/9; thr=5*(thr-32)/9; fri=5*(fri-32)/9; sat=5*(sat-32)/9; sun=5*(sun-32)/9; run; As you can see, the assignment statements perform the same calculation on each variable in this series of statements. Only the name of the variable changes in each statement. By grouping the variables into a one-dimensional array, you can process the variables in a DO loop. You use fewer statements, and the DATA step program is more easily modified or corrected. data work.report; set master.temps; array wkday(7) mon tue wed thr fri sat sun; do i=1 to 7; wkday(i)=5*(wkday(i)-32)/9; end; run; You learn other uses for arrays as you continue through this lesson.