20  INPUT "1st number";N1
30  INPUT "op(+,-,*,/)";OP$
40  INPUT "2nd number";N2
60  IF OP$ = "+" THEN A=N1+N2
70  IF OP$ = "-" THEN A=N1-N2
80  IF OP$ = "*" THEN A=N1*N2
90  IF OP$ = "/" THEN A=N1/N2
100 PRINT A