Let's divide 51718244 by 409
The aim is to understand the frequency of 409 in 51718244.

On to step 1:
409 can be fit into 5 0 times, resulting in a remainder of 5.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 5, we get 5.
Fetch the next digit (1) from the dividend, attach it to 5 and continue: 51 / 409

Going ahead to step 2:
409 can be fit into 51 0 times, resulting in a remainder of 51.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 51 leaves us with 51.
Take the next digit (7) from the dividend and append it to 51, then repeat: 517 / 409

Advancing to step 3:
409 goes into 517 1 times with a remainder of 108.
Write down 1 as next digit of the result. 
Result so far: 1.0
If we take 409 away from 517, we end up with 108.
Fetch the next digit (1) from the dividend, attach it to 108 and continue: 1081 / 409

On to step 4:
The number 409 fits into 1081 2 times, leaving a remainder of 263.
Record the quotient 2 as the next digit in the result. 
Result so far: 12.0
If we subtract 818 from 1081, we get 263.
Include the next digit (8) from the dividend after 263, then repeat: 2638 / 409

Moving on to step 5:
When dividing 2638 by 409, we get 6 with a remainder of 184.
The number 6 becomes the next digit in our result. 
Result so far: 126.0
Deduct 2454 from 2638 and we're left with 184.
Bring next digit (2) of the dividend behind the 184 and repeat the process: 1842 / 409

Moving on to step 6:
The number 409 fits into 1842 4 times, leaving a remainder of 206.
Use 4 as the next digit of our solution. 
Result so far: 1264.0
Deduct 1636 from 1842 and we're left with 206.
Bring next digit (4) of the dividend behind the 206 and repeat the process: 2064 / 409

Advancing to step 7:
If we divide 2064 by 409, we get 5 and a remainder of 19.
The number 5 becomes the next digit in our result. 
Result so far: 12645.0
Subtract 2045 from 2064 to get 19.
Fetch the next digit (4) from the dividend, attach it to 19 and continue: 194 / 409

Let's proceed to step 8:
When dividing 194 by 409, we get 0 with a remainder of 194.
Put 0 as the next digit of the answer. 
Result so far: 126450.0
If we take 0 away from 194, we end up with 194.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1940, and continue the process.

Let's proceed to step 9:
409 can be fit into 1940 4 times, resulting in a remainder of 304.
Put 4 as the next digit of the answer. 
Result so far: 126450.4
If we take 1636 away from 1940, we end up with 304.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3040, and continue the process.

Let's proceed to step 10:
When dividing 3040 by 409, we get 7 with a remainder of 177.
Write down 7 as next digit of the result. 
Result so far: 126450.47
If we take 2863 away from 3040, we end up with 177.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1770, and continue the process.

Step 11:
409 goes into 1770 4 times with a remainder of 134.
Use 4 as the next digit of our solution. 
Result so far: 126450.474
Deduct 1636 from 1770 and we're left with 134.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1340, and continue the process.

Going ahead to step 12:
409 goes into 1340 3 times with a remainder of 113.
Record the quotient 3 as the next digit in the result. 
Result so far: 126450.4743
If we take 1227 away from 1340, we end up with 113.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1130, and continue the process.

Moving on to step 13:
409 can be fit into 1130 2 times, resulting in a remainder of 312.
Record the quotient 2 as the next digit in the result. 
Result so far: 126450.47432
If we take 818 away from 1130, we end up with 312.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3120, and continue the process.

Let's proceed to step 14:
If we divide 3120 by 409, we get 7 and a remainder of 257.
Use 7 as the next digit of our solution. 
Result so far: 126450.474327
If we take 2863 away from 3120, we end up with 257.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2570, and continue the process.

Advancing to step 15:
409 can be fit into 2570 6 times, resulting in a remainder of 116.
The number 6 becomes the next digit in our result. 
Result so far: 126450.4743276
If we subtract 2454 from 2570, we get 116.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1160, and continue the process.

Advancing to step 16:
409 goes into 1160 2 times with a remainder of 342.
Put 2 as the next digit of the answer. 
Result so far: 126450.47432762
Subtract 818 from 1160 to get 342.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3420, and continue the process.

The final outcome is 126450.47432762, with a leftover of 3.42e-07.