       10 INPUT "A number please : ": n#
       20 PRINT n#;
       30 IF isprime#(n#) THEN
       40   PRINT " is a prime number!"
       50 ELSE
       60   PRINT " is not a prime number..."
       70 ENDIF
       80 
       90 FUNC isprime#(n#) CLOSED
      100   FOR f#:=2 TO n# DIV 2 DO
      110     IF n# MOD f#=0 THEN RETURN 0
      150   ENDFOR f#
      160   RETURN 1
      170 ENDFUNC isprime#
