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# How do you check whether a number is divisible by another number?

I need to test whether each number from 1 to 1000 is a multiple of 3 or a multiple of 5.

I tried this code in Python 2.x:

``````n = 0
s = 0

while (n < 1001):
x = n/3
if isinstance(x, (int, long)):
print 'Multiple of 3!'
s = s + n
if False:
y = n/5
if isinstance(y, (int, long)):
s = s + n

print 'Number: '
print n
print 'Sum:'
print s
n = n + 1
``````

The idea is to try dividing the number and see if the result is an integer. However, I’m not getting the expected result.

How do I test whether the number is an integer?

In 2.x, division like this will produce an integer, discarding the remainder; see How can I force division to be floating point? Division keeps rounding down to 0? for details.

In 3.x, the division will produce a floating-point value; the result is not “an integer” even if it is a whole number, so the `isinstance` check will fail. See Why does integer division yield a float instead of another integer? for details.

If you need the remainder from integer division rather than just testing for divisibility, see Find the division remainder of a number.

• In Python 2.x, integer division always yields an integer.

Nov 3, 2011 at 22:19

• You should be printing “Fizz” and “Buzz”

– wim

Nov 3, 2011 at 23:21

• Project Euler Problem 1 ?

Jan 30, 2013 at 13:56

• This is a special case of finding the remainder when doing integer division.

Oct 27 at 19:20

You do this using the modulus operator, `%`

``````n % k == 0
``````

evaluates true if and only if `n` is an exact multiple of `k`. In elementary maths this is known as the remainder from a division.

In your current approach you perform a division and the result will be either

• always an integer if you use integer division, or
• always a float if you use floating point division.

It’s just the wrong way to go about testing divisibility.

• 0 % 5 == 0 would be True as well, but zero is not exact multiple of zero.

Aug 9, 2017 at 12:41

• @Fusion `0 == 0*5`

Feb 20, 2018 at 23:37

• @Chris_Rands Put that into an answer, people who do code-golf (like me) would be very happy. In fact, I came here looking for a golfed answer like that.

Nov 11, 2018 at 22:29

You can simply use `%` Modulus operator to check divisibility.
For example: `n % 2 == 0` means n is exactly divisible by 2 and `n % 2 != 0` means n is not exactly divisible by 2.

You can use % operator to check divisiblity of a given number

The code to check whether given no. is divisible by 3 or 5 when no. less than 1000 is given below:

``````n=0
while n<1000:
if n%3==0 or n%5==0:
print n,'is multiple of 3 or 5'
n=n+1
``````