00:03
Okay, so let's say that our number x has the digits a, b, c, and d.
00:10
Then if we reverse those digits, the number we get looks like this, d, c, b, a.
00:17
And we know that when we add these, a, b, c, d, c, d, c, b, c, a, we're supposed to get 7, 7777.
00:29
And so that means that d plus a is going to be 7 and c plus b is going to be 7.
00:40
So we're trying to figure out how to make a, b, c, d the smallest possible.
00:47
Well, the smallest digit is 0, but we can't lead our 4 digit number with a 0.
00:52
So after that, the smallest digit is 1...