Sum of Numbers program code:

#initialized variable
total = 0
#a while loop that asks the user to enter a 
#series of positive numbers. The user should
#enter a negative number to signal the end 
#of the series. 
while True:
    number = float(input("Enter a positive number (enter a negative number to end): "))
    if number < 0:
        break
    total += number
#Display the sum of positive numbers 
print("The sum of the positive numbers entered is:", total)

Executed Output:

Enter a positive number (enter a negative number to end): 5
Enter a positive number (enter a negative number to end): 10
Enter a positive number (enter a negative number to end): 20
Enter a positive number (enter a negative number to end): 30
Enter a positive number (enter a negative number to end): 40
Enter a positive number (enter a negative number to end): 95
Enter a positive number (enter a negative number to end): -5
The sum of the positive numbers entered is: 200.0