100 REM Disitinguish the number to be prime or not.
110 INPUT n
120 IF MOD(n,2)=0 THEN
130   IF n=2 THEN PRINT "prime" ELSE PRINT "not prime"
140 ELSE
150   FOR i=3 TO SQR(n) STEP 2
160     IF MOD(n,i)=0 THEN EXIT FOR 
170   NEXT i
180   IF i<=SQR(n) THEN PRINT "not prime" ELSE PRINT "prime"
190 END IF
200 END
