task
Essentially, count the number of occurrences of =={{header| on each task page.

Output:

100 doors: 20 examples.
99 Bottles of Beer: 29 examples.
Abstract type: 10 examples.

Total: X examples.
For a full output, updated periodically, see Rosetta Code/Count examples/Full list.

You'll need to use the Media Wiki API, which you can find out about locally, here, or in Media Wiki's API documentation at, API:Query

      VDU 23,22,640;512;8,16,16,128+8 : REM Enable UTF-8 support
 
      SYS "LoadLibrary", "URLMON.DLL" TO urlmon%
      SYS "GetProcAddress", urlmon%, "URLDownloadToFileA" TO UDTF
      special$ = "+()'"
 
      url$ = "http://www.rosettacode.org/w/api.php?action=query" + \
      \      "&list=categorymembers&cmtitle=Category:Programming_Tasks" + \
      \      "&cmlimit=500&format=xml"
      file$ = @tmp$ + "tasks.xml"
      SYS UDTF, 0, url$, file$, 0, 0 TO fail%
      IF fail% ERROR 100, "File download failed (tasks)"
 
      Total% = 0
      file% = OPENIN(file$)
      WHILE NOT EOF#file%
        a$ = GET$#file%
        i% = 0
        REPEAT
          i% = INSTR(a$, "title=", i%+1)
          IF i% THEN
            j% = INSTR(a$, ">", i%)
            title$ = MID$(a$, i%+7, j%-i%-10)
            REM Replace HTML codes:
            REPEAT
              k% = INSTR(title$, "&")
              IF k% THEN
                l% = INSTR(title$, ";", k%)
                title$ = LEFT$(title$,k%-1) + \
                \        FNhtml(MID$(title$,k%,l%-k%+1)) + MID$(title$,l%+1)
              ENDIF
            UNTIL k% = 0
            t$ = title$
            REM Substitute characters not allowed in a URL:
            FOR s% = 1 TO LEN(special$)
              REPEAT
                s$ = MID$(special$, s%, 1)
                k% = INSTR(t$, s$)
                IF k% t$ = LEFT$(t$,k%-1) + "%" + STR$~ASCs$ + MID$(t$,k%+1)
              UNTIL k% = 0
            NEXT
            url$ = "http://www.rosettacode.org/w/index.php?title=" + t$ + \
            \      "&action=raw"
            file$ = @tmp$ + "title.htm"
            SYS UDTF, 0, url$, file$, 0, 0 TO fail%
            IF fail% ERROR 100, "File download failed " + t$
            examples% = 0
            task% = OPENIN(file$)
            WHILE NOT EOF#task%
              IF INSTR(GET$#task%, "=={{header|") examples% += 1
            ENDWHILE
            CLOSE #task%
            Total% += examples%
            PRINT title$ ": " ; examples% " examples."
          ENDIF
        UNTIL i% = 0
        i% = INSTR(a$, "cmcontinue=")
        IF i% THEN
          CLOSE #file%
          j% = INSTR(a$, """", i%+1)
          k% = INSTR(a$, """", j%+1)
          url$ = "http://www.rosettacode.org/w/api.php?action=query" + \
          \      "&list=categorymembers&cmtitle=Category:Programming_Tasks" + \
          \      "&cmlimit=500&format=xml&cmcontinue=" + MID$(a$,j%+1,k%-j%)
          REPEAT
            i% = INSTR(url$, "|")
            IF i% url$ = LEFT$(url$,i%-1) + "%7C" + MID$(url$,i%+1)
          UNTIL i% = 0
          file$ = @tmp$ + "tasks.xml"
          SYS UDTF, 0, url$, file$, 0, 0 TO fail%
          IF fail% ERROR 100, "File download failed (continue)"
          file% = OPENIN(file$)
        ENDIF
      ENDWHILE
      CLOSE #file%
      PRINT ' "Total: " ; Total% " examples."
      END
 
      DEF FNhtml(h$)
      IF LEFT$(h$,2) = "&#" THEN = CHR$(VALMID$(h$,3))
      CASE h$ OF
        WHEN "&quot;": = """"
      ENDCASE
      = h$