Okay, let's tackle this math problem. We're starting with 509933 and subtracting 72006.

Step 1: We'll start by subtracting the digit 6 and the borrow 0 from 3 in column 1 and get -3.
We add -3 to 10 and get 7 as the first digit of the result.

Step 2: We'll start by subtracting the digit 0 and the borrow 1 from 3 in column 2 and get 2.
2 is the next digit of our result.

Step 3: We'll start by subtracting the digit 0 and the borrow 0 from 9 in column 3 and get 9.
9 is the next digit of our result.

Step 4: We'll start by subtracting the digit 2 and the borrow 0 from 9 in column 4 and get 7.
7 is the next digit of our result.

Step 5: We'll start by subtracting the digit 7 and the borrow 0 from 0 in column 5 and get -7.
We add -7 to 10 and get 3 as the next digit of the result.

Step 6: We'll start by subtracting the digit 0 and the borrow 1 from 5 in column 6 and get 4.
4 is the next digit of our result.

So, 509933 - 72006 = 437927.