We look at the division of 630213 by 51 
The aim is to understand the frequency of 51 in 630213.

Step 1:
6 divided by 51 is 0 with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Take the next digit (3) from the dividend and append it to 6, then repeat: 63 / 51

Let's proceed to step 2:
When dividing 63 by 51, we get 1 with a remainder of 12.
Put 1 as the next digit of the answer. 
Result so far: 1.0
Subtract 51 from 63 to get 12.
Include the next digit (0) from the dividend after 12, then repeat: 120 / 51

Let's proceed to step 3:
When dividing 120 by 51, we get 2 with a remainder of 18.
Record the quotient 2 as the next digit in the result. 
Result so far: 12.0
Subtract 102 from 120 to get 18.
Fetch the next digit (2) from the dividend, attach it to 18 and continue: 182 / 51

Going ahead to step 4:
If we divide 182 by 51, we get 3 and a remainder of 29.
Use 3 as the next digit of our solution. 
Result so far: 123.0
Deduct 153 from 182 and we're left with 29.
Bring next digit (1) of the dividend behind the 29 and repeat the process: 291 / 51

Let's proceed to step 5:
51 goes into 291 5 times with a remainder of 36.
Write down 5 as next digit of the result. 
Result so far: 1235.0
The remainder is 36 after subtracting 255 from 291.
Bring next digit (3) of the dividend behind the 36 and repeat the process: 363 / 51

Moving on to step 6:
When dividing 363 by 51, we get 7 with a remainder of 6.
Record the quotient 7 as the next digit in the result. 
Result so far: 12357.0
Deduct 357 from 363 and we're left 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:
The number 51 fits into 60 1 times, leaving a remainder of 9.
The next digit of our result is 1. 
Result so far: 12357.1
If we take 51 away from 60, we end up 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 8:
The number 51 fits into 90 1 times, leaving a remainder of 39.
The next digit of our result is 1. 
Result so far: 12357.11
If we subtract 51 from 90, we get 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

The final result is 12357.11 with a remainder of 0.039.