Let's divide 173739 by 21
The aim is to understand the frequency of 21 in 173739.

On to step 1:
The number 21 fits into 1 0 times, leaving a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 1 and we're left with 1.
Append the next digit (7) from the dividend to 1 and continue with: 17 / 21

On to step 2:
21 goes into 17 0 times with a remainder of 17.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 17 leaves us with 17.
Grab the next digit (3) from the dividend, add it to 17, then carry on: 173 / 21

On to step 3:
If we divide 173 by 21, we get 8 and a remainder of 5.
Write down 8 as next digit of the result. 
Result so far: 8.0
The remainder is 5 after subtracting 168 from 173.
Fetch the next digit (7) from the dividend, attach it to 5 and continue: 57 / 21

Advancing to step 4:
The number 21 fits into 57 2 times, leaving a remainder of 15.
Write down 2 as next digit of the result. 
Result so far: 82.0
If we take 42 away from 57, we end up with 15.
Bring next digit (3) of the dividend behind the 15 and repeat the process: 153 / 21

Step 5:
When dividing 153 by 21, we get 7 with a remainder of 6.
Record the quotient 7 as the next digit in the result. 
Result so far: 827.0
Deduct 147 from 153 and we're left with 6.
Grab the next digit (9) from the dividend, add it to 6, then carry on: 69 / 21

Moving on to step 6:
69 divided by 21 is 3 with a remainder of 6.
Record the quotient 3 as the next digit in the result. 
Result so far: 8273.0
The remainder is 6 after subtracting 63 from 69.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 7:
The number 21 fits into 60 2 times, leaving a remainder of 18.
The next digit of our result is 2. 
Result so far: 8273.2
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.

Step 8:
21 goes into 180 8 times with a remainder of 12.
The next digit of our result is 8. 
Result so far: 8273.28
Deduct 168 from 180 and we're left with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Moving on to step 9:
21 goes into 120 5 times with a remainder of 15.
The next digit of our result is 5. 
Result so far: 8273.285
The remainder is 15 after subtracting 105 from 120.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

On to step 10:
If we divide 150 by 21, we get 7 and a remainder of 3.
Record the quotient 7 as the next digit in the result. 
Result so far: 8273.2857
If we subtract 147 from 150, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Step 11:
21 goes into 30 1 times with a remainder of 9.
The next digit of our result is 1. 
Result so far: 8273.28571
Subtracting 21 from 30 leaves us 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.

Step 12:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 8273.285714
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

On to step 13:
60 divided by 21 is 2 with a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 8273.2857142
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.

On to step 14:
180 divided by 21 is 8 with a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 8273.28571428
If we subtract 168 from 180, we 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.

The quotient of the division is 8273.28571428, and the remainder is 1.2e-08.