Khan/khan-exercises — Issue #7842: Divisibility - Divisibility problem has incorrect answer
Author: KhanBugz
Created: 2011-12-05 20:31:45+00:00
State: open
Labels: firefox, wrong-or-unclear

Reporter: weirdfish13@yahoo.com

The problem is: All numbers divisible by 23 and 10 are also divisible by which of the following? The possible answers are: 228, 46, 152, 71, 42. None of these answers are correct because one of the prime factors of 10 is 5 and none of these answers are divisible by 5. According to the hints, the correct answer is 46, but this is wrong because the prime factors of 46 are 23 x 2; there is no 5. The smallest correct answer would be 230, because the prime factorization of this is 23 x 2 x 5.

[divisibility.html?seed=116&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/divisibility.html?seed=116&problem=0&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/divisibility.html?seed=116&problem=0&debug&activity=%5B%5B%22hint-activity%22%2C%220%22%2C197%5D%2C%5B%22hint-activity%22%2C%220%22%2C201%5D%2C%5B%22hint-activity%22%2C%220%22%2C202%5D%2C%5B%22hint-activity%22%2C%220%22%2C205%5D%5D)

[]

Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.24) Gecko/20111107 Linux Mint/9 (Isadora) Firefox/3.6.24

MathJax is loaded, ready, queue length: 0