We're dividing 21139851 by 159 
We want to figure out the number of times 21139851 can be divided by 159.

Advancing to step 1:
The number 159 fits into 2 0 times, leaving a remainder of 2.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 159

Step 2:
When dividing 21 by 159, we get 0 with a remainder of 21.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 21, we end up with 21.
Append the next digit (1) from the dividend to 21 and continue with: 211 / 159

Step 3:
When dividing 211 by 159, we get 1 with a remainder of 52.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we take 159 away from 211, we end up with 52.
Fetch the next digit (3) from the dividend, attach it to 52 and continue: 523 / 159

Let's proceed to step 4:
159 goes into 523 3 times with a remainder of 46.
Write down 3 as next digit of the result. 
Result so far: 13.0
Subtracting 477 from 523 leaves us with 46.
Include the next digit (9) from the dividend after 46, then repeat: 469 / 159

Going ahead to step 5:
If we divide 469 by 159, we get 2 and a remainder of 151.
Write down 2 as next digit of the result. 
Result so far: 132.0
If we subtract 318 from 469, we get 151.
Append the next digit (8) from the dividend to 151 and continue with: 1518 / 159

On to step 6:
When dividing 1518 by 159, we get 9 with a remainder of 87.
Use 9 as the next digit of our solution. 
Result so far: 1329.0
Subtracting 1431 from 1518 leaves us with 87.
Include the next digit (5) from the dividend after 87, then repeat: 875 / 159

Moving on to step 7:
159 can be fit into 875 5 times, resulting in a remainder of 80.
The next digit of our result is 5. 
Result so far: 13295.0
Subtract 795 from 875 to get 80.
Fetch the next digit (1) from the dividend, attach it to 80 and continue: 801 / 159

Let's proceed to step 8:
When dividing 801 by 159, we get 5 with a remainder of 6.
Write down 5 as next digit of the result. 
Result so far: 132955.0
If we subtract 795 from 801, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Going ahead to step 9:
159 can be fit into 60 0 times, resulting in a remainder of 60.
Record the quotient 0 as the next digit in the result. 
Result so far: 132955.0
If we subtract 0 from 60, we get 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 600, and continue the process.

Moving on to step 10:
159 goes into 600 3 times with a remainder of 123.
The next digit of our result is 3. 
Result so far: 132955.03
Subtracting 477 from 600 leaves us with 123.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1230, and continue the process.

Let's proceed to step 11:
When dividing 1230 by 159, we get 7 with a remainder of 117.
Write down 7 as next digit of the result. 
Result so far: 132955.037
Deduct 1113 from 1230 and we're left with 117.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1170, and continue the process.

Let's proceed to step 12:
When dividing 1170 by 159, we get 7 with a remainder of 57.
Record the quotient 7 as the next digit in the result. 
Result so far: 132955.0377
If we subtract 1113 from 1170, we get 57.
Since there are no more digits in the dividend, we add a zero to the remainder making it 570, and continue the process.

The final result is 132955.0377 with a remainder of 0.00057.