Python Test (Easy)

def isNumber(a):
    try:
        int(a)
        return True
    except ValueError:
        return False

def pickMenu():
    menuID = str(input())
    
    if menuID == "0":
        return "End program"
    elif menuID == "1":
        return 15
    elif menuID == "2":
        return 16.5
    elif menuID == "3":
        return 10
    elif menuID == "4":
        return 12.5
    elif menuID == "5":
        return 10
    elif menuID == "6":
        return 8
    elif menuID == "7":
        return 11.5
    elif menuID == "8":
        return 12
    else:
        return "[That's not an option]"
        
def pickQuantity(price):
    print("Quantity for the item:")
    print("((Type in 0 to cancel ordering this item))")
    quantity = str(input())
    
    if isNumber(quantity):
        if quantity == "0":
            return "Cancel"
        elif int(quantity) > 0:
            return quantity
        else: 
            return "[That's not an option]"
    else:
        return "[That's not an option]"

total = 0;
ordering = True;

#Main code begins
print("---      Welcome to our restaurant!      ---")

while ordering:
    print("============================================")
    print("(1) Food 1       15k || (5) Drink 1      10k")
    print("(2) Food 2     16.5k || (6) Drink 2       8k")
    print("(3) Food 3       10k || (7) Drink 3    11.5k")
    print("(4) Food 4     12.5k || (8) Drink 4      12k")
    print("============================================\n")
    print("Please choose an item by inputing the number:")
    if total > 0:
        print("((Type in 0 to finish this order))")    
    else:
        print("((Type in 0 to cancel this order))")

    chosenMenu = pickMenu()
    
    if isNumber(chosenMenu):
        while True:
            chosenQuantity = pickQuantity(chosenMenu)
            if isNumber(chosenQuantity):
                total += (float(chosenMenu) * float(chosenQuantity))
                break
            elif chosenQuantity == "Cancel":
                break
            else:
                print(chosenQuantity)
                print("\n")
    elif chosenMenu == "End program":
        ordering = False
    else:
        print(chosenMenu)


if total > 0:
    print("\nTOTAL: " + str(total) + "K")
    
print("\nThank you! See you next time!")