Fix ValueError: could not convert string to float:

You are immediately trying to cast your input to a float, which fails when something other than a number is entered. You could fix this by checking for a blank input before doing the cast:

... count = input('Please enter another number: ') if count == (''): break count = float(count) ... 

You do have a number of other logical errors in your code at this point, but that should at least get you past the value error.

You can try just using a try and catch statement to handle a possible ValueError:

try: count = float(input('Please enter another number: ')) except ValueError: break 

However, I do think it's worth noting that there are other parts of your code that are incorrect, so if you could give a bit more depth into what exactly you are trying to code, we can help you fix other parts if you need it.

Simply you can check weather the input is a number or not

value = (input('Please enter number: ')) total = 0 sum = 0 while value.isnumeric(): second_input = input('Please enter another number: ') if not second_input.isnumeric(): break count = float(second_input) sum =+ (1) total = count + count average = (total+value/sum) print(float(average)) 

Working code with exception handling:

value = "" while True: try: value = float(input('Please enter number: ')) break except: print("Invalid number") total = 0 sum = 1 # It is 1 if including the first value, can be change to 0 if isn't while value == value: try: count = input('Please enter another number: ') count = float(count) sum =+ (1) total = total + count # Changed this line as OP asking for average except ValueError: if count == (''): break else: print("Invalid number, press enter to exit loop.") average = (total+value/sum) print(float(average))