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

Question

I need to test whether each number from 1 to 1000 is a multiple of 3 or a multiple of 5. The way I thought I'd do this would be to divide the number by 3, and if the result is an integer then it would be a multiple of 3. Same with 5.

How do I test whether the number is an integer?

Here is my current code:

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

Answer 1

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.

Answer 2

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.

Answer 3

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

Answer 4

This code appears to do what you are asking for.

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

Or something like

for value in range(1,1000):
    if value % 3 == 0 or value % 5 == 0:
        some_list.append(value)

Or any number of things.

Answer 5

I had the same approach. Because I didn't understand how to use the module(%) operator.

6 % 3 = 0 *This means if you divide 6 by 3 you will not have a remainder, 3 is a factor of 6.

Now you have to relate it to your given problem.

if n % 3 == 0 *This is saying, if my number(n) is divisible by 3 leaving a 0 remainder.

Add your then(print, return) statement and continue your

Answer 6

a = 1400
a1 = 5
a2 = 3

b= str(a/a1)
b1 = str(a/a2)
c =b[(len(b)-2):len(b)]
c1 =b[(len(b1)-2):len(b1)]
if c == ".0":
    print("yeah for 5!")
if c1 == ".0":
    print("yeah for 3!")