We look at the division of 921643 by 51 
The aim is to understand the frequency of 51 in 921643.

Advancing to step 1:
If we divide 9 by 51, we get 0 and a remainder of 9.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 9 to get 9.
Take the next digit (2) from the dividend and append it to 9, then repeat: 92 / 51

Advancing to step 2:
51 goes into 92 1 times with a remainder of 41.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we take 51 away from 92, we end up with 41.
Append the next digit (1) from the dividend to 41 and continue with: 411 / 51

Advancing to step 3:
When dividing 411 by 51, we get 8 with a remainder of 3.
Write down 8 as next digit of the result. 
Result so far: 18.0
Deduct 408 from 411 and we're left with 3.
Include the next digit (6) from the dividend after 3, then repeat: 36 / 51

Moving on to step 4:
The number 51 fits into 36 0 times, leaving a remainder of 36.
Put 0 as the next digit of the answer. 
Result so far: 180.0
If we subtract 0 from 36, we get 36.
Bring next digit (4) of the dividend behind the 36 and repeat the process: 364 / 51

On to step 5:
The number 51 fits into 364 7 times, leaving a remainder of 7.
The number 7 becomes the next digit in our result. 
Result so far: 1807.0
The remainder is 7 after subtracting 357 from 364.
Take the next digit (3) from the dividend and append it to 7, then repeat: 73 / 51

Step 6:
The number 51 fits into 73 1 times, leaving a remainder of 22.
Write down 1 as next digit of the result. 
Result so far: 18071.0
Deduct 51 from 73 and we're left with 22.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

Let's proceed to step 7:
When dividing 220 by 51, we get 4 with a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 18071.4
The remainder is 16 after subtracting 204 from 220.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

On to step 8:
51 goes into 160 3 times with a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 18071.43
Deduct 153 from 160 and we're left with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Let's proceed to step 9:
70 divided by 51 is 1 with a remainder of 19.
The number 1 becomes the next digit in our result. 
Result so far: 18071.431
The remainder is 19 after subtracting 51 from 70.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Advancing to step 10:
When dividing 190 by 51, we get 3 with a remainder of 37.
Put 3 as the next digit of the answer. 
Result so far: 18071.4313
If we subtract 153 from 190, we get 37.
Since there are no more digits in the dividend, we add a zero to the remainder making it 370, and continue the process.

Let's proceed to step 11:
When dividing 370 by 51, we get 7 with a remainder of 13.
The next digit of our result is 7. 
Result so far: 18071.43137
Subtract 357 from 370 to get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Step 12:
51 can be fit into 130 2 times, resulting in a remainder of 28.
Write down 2 as next digit of the result. 
Result so far: 18071.431372
Subtract 102 from 130 to get 28.
Since there are no more digits in the dividend, we add a zero to the remainder making it 280, and continue the process.

Step 13:
If we divide 280 by 51, we get 5 and a remainder of 25.
Put 5 as the next digit of the answer. 
Result so far: 18071.4313725
If we subtract 255 from 280, we get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Step 14:
250 divided by 51 is 4 with a remainder of 46.
Write down 4 as next digit of the result. 
Result so far: 18071.43137254
Subtract 204 from 250 to get 46.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

The quotient of the division is 18071.43137254, and the remainder is 4.6e-08.