We look at the division of 943521 by 51 
We're looking to find how many times 51 goes into 943521.

Moving on to step 1:
When dividing 9 by 51, we get 0 with a remainder of 9.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 9, we get 9.
Append the next digit (4) from the dividend to 9 and continue with: 94 / 51

On to step 2:
51 can be fit into 94 1 times, resulting in a remainder of 43.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we take 51 away from 94, we end up with 43.
Take the next digit (3) from the dividend and append it to 43, then repeat: 433 / 51

On to step 3:
The number 51 fits into 433 8 times, leaving a remainder of 25.
Record the quotient 8 as the next digit in the result. 
Result so far: 18.0
If we take 408 away from 433, we end up with 25.
Take the next digit (5) from the dividend and append it to 25, then repeat: 255 / 51

Moving on to step 4:
The number 51 fits into 255 5 times, leaving a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 185.0
The remainder is 0 after subtracting 255 from 255.
Fetch the next digit (2) from the dividend, attach it to 0 and continue: 2 / 51

Going ahead to step 5:
If we divide 2 by 51, we get 0 and a remainder of 2.
Put 0 as the next digit of the answer. 
Result so far: 1850.0
Subtracting 0 from 2 leaves us with 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 51

Step 6:
When dividing 21 by 51, we get 0 with a remainder of 21.
Write down 0 as next digit of the result. 
Result so far: 18500.0
Subtracting 0 from 21 leaves us with 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

Going ahead to step 7:
The number 51 fits into 210 4 times, leaving a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 18500.4
Subtracting 204 from 210 leaves us with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Moving on to step 8:
When dividing 60 by 51, we get 1 with a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 18500.41
If we subtract 51 from 60, we get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 9:
51 goes into 90 1 times with a remainder of 39.
The next digit of our result is 1. 
Result so far: 18500.411
Subtract 51 from 90 to get 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

The final result is 18500.411 with a remainder of 0.0039.