We're dividing 51451686 by 209 
The aim is to understand the frequency of 209 in 51451686.

Step 1:
209 goes into 5 0 times with a remainder of 5.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 209

Let's proceed to step 2:
209 goes into 51 0 times with a remainder of 51.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 51 to get 51.
Append the next digit (4) from the dividend to 51 and continue with: 514 / 209

Going ahead to step 3:
If we divide 514 by 209, we get 2 and a remainder of 96.
Put 2 as the next digit of the answer. 
Result so far: 2.0
The remainder is 96 after subtracting 418 from 514.
Include the next digit (5) from the dividend after 96, then repeat: 965 / 209

On to step 4:
209 goes into 965 4 times with a remainder of 129.
The number 4 becomes the next digit in our result. 
Result so far: 24.0
Subtract 836 from 965 to get 129.
Bring next digit (1) of the dividend behind the 129 and repeat the process: 1291 / 209

Going ahead to step 5:
1291 divided by 209 is 6 with a remainder of 37.
The next digit of our result is 6. 
Result so far: 246.0
Deduct 1254 from 1291 and we're left with 37.
Grab the next digit (6) from the dividend, add it to 37, then carry on: 376 / 209

Going ahead to step 6:
376 divided by 209 is 1 with a remainder of 167.
Write down 1 as next digit of the result. 
Result so far: 2461.0
The remainder is 167 after subtracting 209 from 376.
Bring next digit (8) of the dividend behind the 167 and repeat the process: 1678 / 209

Moving on to step 7:
When dividing 1678 by 209, we get 8 with a remainder of 6.
Use 8 as the next digit of our solution. 
Result so far: 24618.0
The remainder is 6 after subtracting 1672 from 1678.
Append the next digit (6) from the dividend to 6 and continue with: 66 / 209

On to step 8:
209 can be fit into 66 0 times, resulting in a remainder of 66.
Put 0 as the next digit of the answer. 
Result so far: 246180.0
If we take 0 away from 66, we end up with 66.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Let's proceed to step 9:
When dividing 660 by 209, we get 3 with a remainder of 33.
The next digit of our result is 3. 
Result so far: 246180.3
The remainder is 33 after subtracting 627 from 660.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

Going ahead to step 10:
When dividing 330 by 209, we get 1 with a remainder of 121.
The next digit of our result is 1. 
Result so far: 246180.31
The remainder is 121 after subtracting 209 from 330.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1210, and continue the process.

Advancing to step 11:
The number 209 fits into 1210 5 times, leaving a remainder of 165.
The number 5 becomes the next digit in our result. 
Result so far: 246180.315
If we subtract 1045 from 1210, we get 165.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1650, and continue the process.

On to step 12:
The number 209 fits into 1650 7 times, leaving a remainder of 187.
Put 7 as the next digit of the answer. 
Result so far: 246180.3157
Subtract 1463 from 1650 to get 187.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1870, and continue the process.

Step 13:
209 can be fit into 1870 8 times, resulting in a remainder of 198.
The number 8 becomes the next digit in our result. 
Result so far: 246180.31578
Deduct 1672 from 1870 and we're left with 198.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1980, and continue the process.

Going ahead to step 14:
The number 209 fits into 1980 9 times, leaving a remainder of 99.
Record the quotient 9 as the next digit in the result. 
Result so far: 246180.315789
Deduct 1881 from 1980 and we're left with 99.
Since there are no more digits in the dividend, we add a zero to the remainder making it 990, and continue the process.

Let's proceed to step 15:
990 divided by 209 is 4 with a remainder of 154.
Put 4 as the next digit of the answer. 
Result so far: 246180.3157894
Subtract 836 from 990 to get 154.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1540, and continue the process.

On to step 16:
1540 divided by 209 is 7 with a remainder of 77.
The number 7 becomes the next digit in our result. 
Result so far: 246180.31578947
Subtracting 1463 from 1540 leaves us with 77.
Since there are no more digits in the dividend, we add a zero to the remainder making it 770, and continue the process.

The final result is 246180.31578947 with a remainder of 7.7e-08.