Qbasic Calculator

'QBASIC calculator! Made by Prithak Adhikari
DIM a AS INTEGER
DIM b AS INTEGER
top:
CLS
PRINT "Welcome to Prithak's Calculator"
PRINT
INPUT "Enter the first number"; a
INPUT "Enter the Mathmatical Operator(+,-,*,/,^,MOD)"; oper$
SELECT CASE oper$
    CASE "+"
        INPUT "Enter second number"; b
        sum = a + b
        PRINT "Result: "; sum
        INPUT "Would you like to do it again(y/n)"; ch$
        IF ch$ = "y" THEN GOTO top
        IF ch$ = "n" THEN END
    CASE "-"
        INPUT "Enter second number"; b
        diff = a - b
        PRINT "Result: "; diff
        INPUT "Would you like to do this again(y/n)"; ch$
        IF ch$ = "y" THEN GOTO top
        IF ch$ = "n" THEN END
    CASE "*"
        INPUT "Enter second number"; b
        mult = a * b
        PRINT "Result: "; mult
        INPUT "Would you like to d othis again(y/n)"; ch$
        IF ch$ = "y" THEN GOTO top
        IF ch$ = "n" THEN END

    CASE "/"
        INPUT "Enter second number"; b
        div = a / b
        PRINT "Result: "; div
        INPUT "Would you like to d othis again(y/n)"; ch$
        IF ch$ = "y" THEN GOTO top
        IF ch$ = "n" THEN END
    CASE "^"
        INPUT "Enter second number"; b
        expo = a ^ b
        PRINT "Result: "; expo
        INPUT "Would you like to d othis again(y/n)"; ch$
        IF ch$ = "y" THEN GOTO top
        IF ch$ = "n" THEN END
    CASE "MOD"
        INPUT "Enter second number"; b
        modd = a MOD b
        PRINT "Result: "; modd
        INPUT "Would you like to d othis again(y/n)"; ch$
        IF ch$ = "y" THEN GOTO top
        IF ch$ = "n" THEN END
END SELECT