Sum of divisors in python

In my program, it is supposed to ask the user for a number, then displays all the divisors possible, but in the end, it has to display the sum of all the divisors. I'm having trouble with the last part and would appreciate some help.

My code:

    prompt = int(input("Enter an interger: "))

print("The divisors of the integer you entered are: ")
for i in range(1, prompt+1):
    if(prompt%i==0):
        print(i)
        print(f")

Example if user inputed 20:

The divisors of the integer you entered are:

1

2

4

5

10

20

The sum of the divisors is: 42

Welbog

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asked Oct 1, 2018 at 14:07

3

Just a simple modification of your code can do the trick. like:

prompt = int(input("Enter an interger: "))

print("The divisors of the integer you entered are: ")
divisor_sum = 0 #updated line
for i in range(1, prompt+1):
    if(prompt%i==0):
        print(i)
        divisor_sum+=i #calculate sum of all divisors

print("The sum of divisors " + str(divisor_sum)) #print the sum of divisors

Also you can use list comprehension to make your program shorter and smarter, like:

prompt = int(input("Enter an interger: "))

divisors = [i for i in range(1,prompt+1) if prompt%i==0]
divisor_sum = sum(divisors)

print("The divisors of the integer you entered are: ")
for i in divisors:
    print(i)

print("The sum of divisors " + str(divisor_sum))

answered Oct 1, 2018 at 14:10

Taohidul IslamTaohidul Islam

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You just need a variable to store the sum. I have used s. Rest all code is perfectly fine except print(f"). It is unused and gives syntax error due to incomplete ". Moreover, f is not defined

prompt = int(input("Enter an interger: "))
s=0
print("The divisors of the integer you entered are: ")

for i in range(1, prompt+1):
    if(prompt%i==0):
        s += i
        print(i)
print ("The sum of the divisors is: %d" %s)

Output

Enter an interger: 20
The divisors of the integer you entered are: 
1
2
4
5
10
20
The sum of the divisors is: 42

answered Oct 1, 2018 at 14:09

SheldoreSheldore

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Another approach is storing the list of valid divisors in a container of some sorts. In this case the appropriate "container" is a list. This has the advantage that you store the divisors for later use.

prompt = int(input("Enter an interger: "))
divisors = []
print("The divisors of the integer you entered are: ")

for i in range(1, prompt+1):
    if(prompt%i==0):
        print(i)
        divisors.append(i)

print("The sum of divisors " + sum(divisors)) #print the sum of divisors
# max(divisors)
# min(divisors)
# etc...

answered Oct 1, 2018 at 14:17

redactedredacted

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Well, This question reminded me about a question i solved in project Euler ,and i did it in O(sqrt(n)) complexity .

if you consider 9 ,

We dont need to consider till 9 to get all factors . We just need to consider till 3 if we have X as divisor then prompt/X is also a divisor . With this property you could make the algorithm more efficient

import time
from math import sqrt
prompt = int(input("Enter an interger: "))
start =time.time()
print("The divisors of the integer you entered are: ")

sumofdivisors=0 
for divisor in range(1, int(sqrt(prompt))+1):
    if(prompt%divisor==0):
        sumofdivisors+=divisor
        sumofdivisors+=(prompt/divisor)
        if (divisor==prompt/divisor):
            sumofdivisors-=divisor
            print(divisor)
        else:
            print(divisor)
            print(prompt/divisor)
print("sum is",sumofdivisors)
end=time.time()
print("time taken is",end-start)

OUTPUT

Enter an interger: 8
The divisors of the integer you entered are: 
1
8.0
2
4.0
sum is 15.0
time took =  0.0002665519714355469

answered Oct 1, 2018 at 14:14

Albin PaulAlbin Paul

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prompt = int(input("Enter an interger: "))

print("The divisors of the integer you entered are: ")
total= 0
for i in range(1, prompt+1):
    if(prompt%i==0):
        print(i)
        total+= i

print("The sum of the divisors is:{}".format(total))

Output:

Enter an interger: 20
The divisors of the integer you entered are: 
1
2
4
5
10
20
The sum of the divisors is:42

answered Oct 1, 2018 at 14:19

Mathematically speaking, when you are summing the divisors of a number you do not include the number in question. the +1 normally added the range function is not needed, and will produce in incorrect result. The following Wikipedia article on amicable pairs can be used as a reference.

https://en.wikipedia.org/wiki/Amicable_numbers

answered May 20 at 21:27

1

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