Not being as good as some of the people around here, I'd probably do a sort (copy?) with the input being appended/replaced with a numeric one (and a constant key?), sum the one (on the key?) and format the output with the summed one and whatever constant you like.
I usually don't answer Syncsort questions, but I feel compelled to point out that the "solution" arrived at here is unnecessarily complicated. For a simple DFSORT solution which will probably work with Syncsort as well, see "Display the number of input or output records" Smart DFSORT Trick at:
Note that the COUNT operator of DFSORT's ICETOOL displays the count in a message in TOOLMSG - COUNT does not create an output data set so you can't count the records with OUTFIL. To get the count in a data set, use the trick indicated above. You can do the same thing with ICETOOL using a COPY operator and an OUTFIL statement.