freecodecamp--freecodecamp/curriculum/challenges/english/blocks/daily-coding-challenges-python/68f6587287ad1f4ad39b0c83.md

id, title, challengeType, dashedName

id	title	challengeType	dashedName
68f6587287ad1f4ad39b0c83	Challenge 97: GCD	29	challenge-97

--description--

Given two positive integers, return their greatest common divisor (GCD).

• The GCD of two integers is the largest number that divides evenly into both numbers without leaving a remainder.

For example, the divisors of 4 are 1, 2, and 4. The divisors of 6 are 1, 2, 3, and 6. So given 4 and 6, return 2, the largest number that appears in both sets of divisors.

--hints--

gcd(4, 6) should return 2.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(gcd(4, 6), 2)`)
}})

gcd(20, 15) should return 5.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(gcd(20, 15), 5)`)
}})

gcd(13, 17) should return 1.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(gcd(13, 17), 1)`)
}})

gcd(654, 456) should return 6.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(gcd(654, 456), 6)`)
}})

gcd(3456, 4320) should return 864.

({test: () => { runPython(`
from unittest import TestCase
TestCase().assertEqual(gcd(3456, 4320), 864)`)
}})

--seed--

--seed-contents--

def gcd(x, y):

    return x

--solutions--

def gcd(x, y):
    while y != 0:
        x, y = y, x % y
    return x