121659 divided by 21 
The aim is to understand the frequency of 21 in 121659.

Advancing to step 1:
The number 21 fits into 1 0 times, leaving a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Include the next digit (2) from the dividend after 1, then repeat: 12 / 21

Step 2:
21 can be fit into 12 0 times, resulting in a remainder of 12.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 12 after subtracting 0 from 12.
Include the next digit (1) from the dividend after 12, then repeat: 121 / 21

Advancing to step 3:
If we divide 121 by 21, we get 5 and a remainder of 16.
Write down 5 as next digit of the result. 
Result so far: 5.0
If we take 105 away from 121, we end up with 16.
Fetch the next digit (6) from the dividend, attach it to 16 and continue: 166 / 21

Advancing to step 4:
21 goes into 166 7 times with a remainder of 19.
Record the quotient 7 as the next digit in the result. 
Result so far: 57.0
Subtract 147 from 166 to get 19.
Grab the next digit (5) from the dividend, add it to 19, then carry on: 195 / 21

Moving on to step 5:
21 can be fit into 195 9 times, resulting in a remainder of 6.
Record the quotient 9 as the next digit in the result. 
Result so far: 579.0
If we take 189 away from 195, we end up with 6.
Take the next digit (9) from the dividend and append it to 6, then repeat: 69 / 21

Step 6:
69 divided by 21 is 3 with a remainder of 6.
Use 3 as the next digit of our solution. 
Result so far: 5793.0
Subtracting 63 from 69 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.

Step 7:
When dividing 60 by 21, we get 2 with a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 5793.2
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.

Step 8:
If we divide 180 by 21, we get 8 and a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 5793.28
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.

Advancing to step 9:
If we divide 120 by 21, we get 5 and a remainder of 15.
The next digit of our result is 5. 
Result so far: 5793.285
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.

Moving on to step 10:
When dividing 150 by 21, we get 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 5793.2857
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.

Going ahead to step 11:
If we divide 30 by 21, we get 1 and a remainder of 9.
Write down 1 as next digit of the result. 
Result so far: 5793.28571
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.

Going ahead to step 12:
When dividing 90 by 21, we get 4 with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 5793.285714
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.

Step 13:
21 goes into 60 2 times with a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 5793.2857142
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.

Advancing to step 14:
180 divided by 21 is 8 with a remainder of 12.
Put 8 as the next digit of the answer. 
Result so far: 5793.28571428
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.

The quotient of the division is 5793.28571428, and the remainder is 1.2e-08.