How to print only the last result of an array of sum in python

Question

I want to calculate the sum of the natural numbers from 1 up to an input number. I wrote this code:

number=int(input("enter a natural number"))
if number<0: 
    print("The number is not positive") 
else:   
   n=0   
   for i in range (1,number+1):
        n+=i
        print(n)

But it prints multiple numbers instead. For example, if the user puts five, the program should print 15, but I get this:

1
3
6
10
15

How can I fix the code so that only 15 appears?

Answer 1

You have all the steps because your print statement is in your for loop. Change it like this:

number = int(input("Enter a positive natural number: "))
if number < 0:
    print("The number needs to be positive")
    exit()  # Stops the program

result = 0
for i in range(1, number + 1):
    result += i

print(result)    # We print after the calculations

There's also a mathematical alternative (see here):

number = int(input("Enter a positive natural number: "))
if number < 0:
    print("The number needs to be positive")
    exit()  # Stops the program
print(number * (number + 1) / 2)