What is the least four-digit positive integer, with all different digits, that is divisible by each of its digits?
Sorry I am not CPhill, but I will help :D
Start with 0, and go up to 9999.
0 divided by anything can't be a number, so 0 is not the answer.
Every whole number is divisible by 1.
2 should be in the hundreds place to make a small number.
MAKE SURE THE NUMBER IS EVEN.
You can put a 3 in the tens place, but you cannot use any other odd numbers.
We can't use 4, since 4 is not divisible by 3, or 5.
6 is the next number that works
Hence, 1236 is the smallest number divisible by its digits.
Hope this helped!