We look at the division of 512621 by 51 
The aim is to understand the frequency of 51 in 512621.

Advancing to step 1:
When dividing 5 by 51, we get 0 with a remainder of 5.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 5 after subtracting 0 from 5.
Fetch the next digit (1) from the dividend, attach it to 5 and continue: 51 / 51

Let's proceed to step 2:
51 can be fit into 51 1 times, resulting in a remainder of 0.
Write down 1 as next digit of the result. 
Result so far: 1.0
Deduct 51 from 51 and we're left with 0.
Take the next digit (2) from the dividend and append it to 0, then repeat: 2 / 51

On to step 3:
When dividing 2 by 51, we get 0 with a remainder of 2.
The next digit of our result is 0. 
Result so far: 10.0
The remainder is 2 after subtracting 0 from 2.
Fetch the next digit (6) from the dividend, attach it to 2 and continue: 26 / 51

Step 4:
51 goes into 26 0 times with a remainder of 26.
The number 0 becomes the next digit in our result. 
Result so far: 100.0
Deduct 0 from 26 and we're left with 26.
Fetch the next digit (2) from the dividend, attach it to 26 and continue: 262 / 51

Going ahead to step 5:
51 can be fit into 262 5 times, resulting in a remainder of 7.
The number 5 becomes the next digit in our result. 
Result so far: 1005.0
If we subtract 255 from 262, we get 7.
Bring next digit (1) of the dividend behind the 7 and repeat the process: 71 / 51

Advancing to step 6:
When dividing 71 by 51, we get 1 with a remainder of 20.
Use 1 as the next digit of our solution. 
Result so far: 10051.0
Subtract 51 from 71 to get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 7:
If we divide 200 by 51, we get 3 and a remainder of 47.
Use 3 as the next digit of our solution. 
Result so far: 10051.3
Subtracting 153 from 200 leaves us with 47.
Since there are no more digits in the dividend, we add a zero to the remainder making it 470, and continue the process.

Step 8:
51 can be fit into 470 9 times, resulting in a remainder of 11.
Write down 9 as next digit of the result. 
Result so far: 10051.39
The remainder is 11 after subtracting 459 from 470.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Step 9:
When dividing 110 by 51, we get 2 with a remainder of 8.
Use 2 as the next digit of our solution. 
Result so far: 10051.392
Deduct 102 from 110 and we're left with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Let's proceed to step 10:
If we divide 80 by 51, we get 1 and a remainder of 29.
The number 1 becomes the next digit in our result. 
Result so far: 10051.3921
Subtract 51 from 80 to get 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

Going ahead to step 11:
The number 51 fits into 290 5 times, leaving a remainder of 35.
Record the quotient 5 as the next digit in the result. 
Result so far: 10051.39215
The remainder is 35 after subtracting 255 from 290.
Since there are no more digits in the dividend, we add a zero to the remainder making it 350, and continue the process.

Step 12:
When dividing 350 by 51, we get 6 with a remainder of 44.
The number 6 becomes the next digit in our result. 
Result so far: 10051.392156
The remainder is 44 after subtracting 306 from 350.
Since there are no more digits in the dividend, we add a zero to the remainder making it 440, and continue the process.

Going ahead to step 13:
440 divided by 51 is 8 with a remainder of 32.
The number 8 becomes the next digit in our result. 
Result so far: 10051.3921568
If we take 408 away from 440, we end up with 32.
Since there are no more digits in the dividend, we add a zero to the remainder making it 320, and continue the process.

Step 14:
51 can be fit into 320 6 times, resulting in a remainder of 14.
The next digit of our result is 6. 
Result so far: 10051.39215686
If we subtract 306 from 320, we get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

After the division, we end up with 10051.39215686 and a remainder of 1.4e-08.