How do I find out the sum of digits of a number in Python

Question

Hi all, pretty simple question. Let me explain with an example:

Let us say my input is a number - 545.

I want the output to be 14 (5+4+5)

What is the quickest and the easiest way to go about doing this?

I was checking up online and I found that using the sum function helps. This is what I used: 

sum(map(int, str(number)))

I want to know what is the best method to use if speed is my priority and if there are any other methods which I could make use of. 

All help appreciated!

Comments

nbr = str(545)
lst = list(nbr)
sum=0
for i in lst:
    k=int(i)
    sum=k+sum
    print (int(i))
print(sum)

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Answer 1

Hi, good question. If you are considering to only work with integers then you can go about using the following syntax to do it in the most efficient way possible. Check it out:

def sum_digits(n):
    s = 0
    while n:
        s += n % 10
        n //= 10
    return s

However, the same can be done using the divmod function as well. Check this:

def sum_digits2(n):
    s = 0
    while n:
        n, remainder = divmod(n, 10)
        s += remainder
    return s

Also, wanted to tell you that whatever you have posted is perfectly right to solve the purpose. but there is a faster way to go about doing it and this is by using a version without any augmented assignments. Check it out:

def sum_digits3(n):
   r = 0
   while n:
       r, n = r + n % 10, n // 10
   return r

Hope this helps!