166746 ÷ 21 
We want to figure out the number of times 166746 can be divided by 21.

On to step 1:
21 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 1 after subtracting 0 from 1.
Include the next digit (6) from the dividend after 1, then repeat: 16 / 21

Step 2:
16 divided by 21 is 0 with a remainder of 16.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we take 0 away from 16, we end up with 16.
Take the next digit (6) from the dividend and append it to 16, then repeat: 166 / 21

Step 3:
21 can be fit into 166 7 times, resulting in a remainder of 19.
The next digit of our result is 7. 
Result so far: 7.0
Subtracting 147 from 166 leaves us with 19.
Bring next digit (7) of the dividend behind the 19 and repeat the process: 197 / 21

Moving on to step 4:
When dividing 197 by 21, we get 9 with a remainder of 8.
The next digit of our result is 9. 
Result so far: 79.0
The remainder is 8 after subtracting 189 from 197.
Bring next digit (4) of the dividend behind the 8 and repeat the process: 84 / 21

Step 5:
84 divided by 21 is 4 with a remainder of 0.
Write down 4 as next digit of the result. 
Result so far: 794.0
Subtract 84 from 84 to get 0.
Append the next digit (6) from the dividend to 0 and continue with: 6 / 21

Step 6:
If we divide 6 by 21, we get 0 and a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 7940.0
If we subtract 0 from 6, 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.

Step 7:
60 divided by 21 is 2 with a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 7940.2
Subtracting 42 from 60 leaves us with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

On to step 8:
If we divide 180 by 21, we get 8 and a remainder of 12.
Record the quotient 8 as the next digit in the result. 
Result so far: 7940.28
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Advancing to step 9:
21 can be fit into 120 5 times, resulting in a remainder of 15.
The next digit of our result is 5. 
Result so far: 7940.285
Subtract 105 from 120 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Step 10:
The number 21 fits into 150 7 times, leaving a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 7940.2857
Deduct 147 from 150 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 11:
If we divide 30 by 21, we get 1 and a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 7940.28571
Deduct 21 from 30 and we're left with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 12:
90 divided by 21 is 4 with a remainder of 6.
Write down 4 as next digit of the result. 
Result so far: 7940.285714
Subtract 84 from 90 to 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 13:
60 divided by 21 is 2 with a remainder of 18.
Put 2 as the next digit of the answer. 
Result so far: 7940.2857142
Subtract 42 from 60 to get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Going ahead to step 14:
If we divide 180 by 21, we get 8 and a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 7940.28571428
The remainder is 12 after subtracting 168 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Our division results in 7940.28571428 with a remaining 1.2e-08.