determining a interger if divisible without using modulus

[acejhon]

helo guys good day...

i have a problem in python programming... im new to this langauage..

im having a bit problem on creating a program in python that would determine if the integer is divisible by 3 or not without using a modulus?

im glad if you can help me .... im willing to know more about this language...

thanks...... =)

[griswolf]

Modulus operator is the right thing to use. Why not? However, here's another way:

def divisibleBy3theHardWay(anInt):
  while anInt > 10:
    sum = 0
    for c in str(anInt):
      sum += int(c) # I'm assuming anInt is indeed an int
    anInt = sum
  return anInt in (0,3,6,9)

This method is also known as 'striking out threes', and it is much much slower than using the '%' operator on the int.

Exercise for the reader: Prove this is a valid test for 'divisible by three'. Hint: what is (10^N)%3?

[woooee]

Divide by 3, multiply the result by 3, and compare to the original number, assuming that you are using integers only.