total_sum = 0
for i in range(1000):
    if (i%3 == 0 or i%5 == 0):
        total_sum = total_sum+i
print total_sum  

You should leave your numbers, variables and operators some space to breathe by adding some horizontal space between them which improves readability a lot.

total_sum = 0
for i in range(1000):
    if (i % 3 == 0 or i % 5 == 0):
        total_sum = total_sum + i
print total_sum  

As natural numbers aren't explictly defined containg 0 you could also use a start parameter of the range() method like so

total_sum = 0
for i in range(1, 1000):
    if (i % 3 == 0 or i % 5 == 0):
        total_sum = total_sum + i
print total_sum  

total_sum = 0
for i in range(1000):
    if (i%3 == 0 or i%5 == 0):
        total_sum = total_sum+i
print total_sum  

You should leave your numbers, variables and operators some space to breathe by adding some horizontal space between them which improves readability a lot.

total_sum = 0
for i in range(1000):
    if (i % 3 == 0 or i % 5 == 0):
        total_sum = total_sum + i
print total_sum  

As natural numbers aren't explictly defined containing 0 you could also use the two-parameter form of the range() function and specify the start parameter like so

total_sum = 0
for i in range(1, 1000):
    if (i % 3 == 0 or i % 5 == 0):
        total_sum = total_sum + i
print total_sum  

total_sum = 0
for i in range(1000):
    if (i%3 == 0 or i%5 == 0):
        total_sum = total_sum+i
print total_sum  

You should leave your numbers, variables and operators some space to breathe by adding some horizontal space between them which improves readability a lot.

total_sum = 0
for i in range(1000):
    if (i % 3 == 0 or i % 5 == 0):
        total_sum = total_sum + i
print total_sum  

As natural numbers aren't explictly defined containg 0 you could also use a start parameter like so

total_sum = 0
for i in range(1, 1000):
    if (i % 3 == 0 or i % 5 == 0):
        total_sum = total_sum + i
print total_sum  

total_sum = 0
for i in range(1000):
    if (i%3 == 0 or i%5 == 0):
        total_sum = total_sum+i
print total_sum  

You should leave your numbers, variables and operators some space to breathe by adding some horizontal space between them which improves readability a lot.

total_sum = 0
for i in range(1000):
    if (i % 3 == 0 or i % 5 == 0):
        total_sum = total_sum + i
print total_sum  

As natural numbers aren't explictly defined containg 0 you could also use a start parameter of the range() method like so

total_sum = 0
for i in range(1, 1000):
    if (i % 3 == 0 or i % 5 == 0):
        total_sum = total_sum + i
print total_sum