We look at the division of 66158 by 21 
We're looking to find how many times 21 goes into 66158.

Going ahead to step 1:
21 can be fit into 6 0 times, resulting in a remainder of 6.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Append the next digit (6) from the dividend to 6 and continue with: 66 / 21

Let's proceed to step 2:
When dividing 66 by 21, we get 3 with a remainder of 3.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
The remainder is 3 after subtracting 63 from 66.
Fetch the next digit (1) from the dividend, attach it to 3 and continue: 31 / 21

Going ahead to step 3:
The number 21 fits into 31 1 times, leaving a remainder of 10.
Use 1 as the next digit of our solution. 
Result so far: 31.0
If we take 21 away from 31, we end up with 10.
Grab the next digit (5) from the dividend, add it to 10, then carry on: 105 / 21

Step 4:
When dividing 105 by 21, we get 5 with a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 315.0
Subtract 105 from 105 to get 0.
Append the next digit (8) from the dividend to 0 and continue with: 8 / 21

Let's proceed to step 5:
21 can be fit into 8 0 times, resulting in a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 3150.0
Subtract 0 from 8 to get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Moving on to step 6:
When dividing 80 by 21, we get 3 with a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 3150.3
Deduct 63 from 80 and we're left with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Going ahead to step 7:
If we divide 170 by 21, we get 8 and a remainder of 2.
Put 8 as the next digit of the answer. 
Result so far: 3150.38
The remainder is 2 after subtracting 168 from 170.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 8:
20 divided by 21 is 0 with a remainder of 20.
Put 0 as the next digit of the answer. 
Result so far: 3150.38
Deduct 0 from 20 and we're left with 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Step 9:
When dividing 200 by 21, we get 9 with a remainder of 11.
Write down 9 as next digit of the result. 
Result so far: 3150.3809
The remainder is 11 after subtracting 189 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 10:
The number 21 fits into 110 5 times, leaving a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 3150.38095
Deduct 105 from 110 and we're left with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Going ahead to step 11:
50 divided by 21 is 2 with a remainder of 8.
Put 2 as the next digit of the answer. 
Result so far: 3150.380952
The remainder is 8 after subtracting 42 from 50.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Going ahead to step 12:
If we divide 80 by 21, we get 3 and a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 3150.3809523
Deduct 63 from 80 and we're left with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Step 13:
21 can be fit into 170 8 times, resulting in a remainder of 2.
Write down 8 as next digit of the result. 
Result so far: 3150.38095238
Subtracting 168 from 170 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

The final outcome is 3150.38095238, with a leftover of 2e-09.