Okay, let's tackle this math problem. We're starting with 644393 and subtracting 17014.

Step 1: We'll start by subtracting the digit 4 and the borrow 0 from 3 in column 1 and get -1.
We add -1 to 10 and get 9 as the first digit of the result.

Step 2: We'll start by subtracting the digit 1 and the borrow 1 from 9 in column 2 and get 7.
7 is the next digit of our result.

Step 3: We'll start by subtracting the digit 0 and the borrow 0 from 3 in column 3 and get 3.
3 is the next digit of our result.

Step 4: We'll start by subtracting the digit 7 and the borrow 0 from 4 in column 4 and get -3.
We add -3 to 10 and get 7 as the next digit of the result.

Step 5: We'll start by subtracting the digit 1 and the borrow 1 from 4 in column 5 and get 2.
2 is the next digit of our result.

Step 6: We'll start by subtracting the digit 0 and the borrow 0 from 6 in column 6 and get 6.
6 is the next digit of our result.

So, 644393 - 17014 = 627379.