83538419 divided by 661 
The aim is to understand the frequency of 661 in 83538419.

Let's proceed to step 1:
The number 661 fits into 8 0 times, leaving a remainder of 8.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Append the next digit (3) from the dividend to 8 and continue with: 83 / 661

Moving on to step 2:
When dividing 83 by 661, we get 0 with a remainder of 83.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 83 and we're left with 83.
Append the next digit (5) from the dividend to 83 and continue with: 835 / 661

Advancing to step 3:
661 goes into 835 1 times with a remainder of 174.
The next digit of our result is 1. 
Result so far: 1.0
If we subtract 661 from 835, we get 174.
Fetch the next digit (3) from the dividend, attach it to 174 and continue: 1743 / 661

Moving on to step 4:
661 can be fit into 1743 2 times, resulting in a remainder of 421.
Use 2 as the next digit of our solution. 
Result so far: 12.0
If we take 1322 away from 1743, we end up with 421.
Bring next digit (8) of the dividend behind the 421 and repeat the process: 4218 / 661

Advancing to step 5:
661 goes into 4218 6 times with a remainder of 252.
Put 6 as the next digit of the answer. 
Result so far: 126.0
The remainder is 252 after subtracting 3966 from 4218.
Bring next digit (4) of the dividend behind the 252 and repeat the process: 2524 / 661

Going ahead to step 6:
2524 divided by 661 is 3 with a remainder of 541.
Write down 3 as next digit of the result. 
Result so far: 1263.0
If we take 1983 away from 2524, we end up with 541.
Bring next digit (1) of the dividend behind the 541 and repeat the process: 5411 / 661

Going ahead to step 7:
The number 661 fits into 5411 8 times, leaving a remainder of 123.
The next digit of our result is 8. 
Result so far: 12638.0
If we subtract 5288 from 5411, we get 123.
Fetch the next digit (9) from the dividend, attach it to 123 and continue: 1239 / 661

Step 8:
661 can be fit into 1239 1 times, resulting in a remainder of 578.
Write down 1 as next digit of the result. 
Result so far: 126381.0
If we subtract 661 from 1239, we get 578.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5780, and continue the process.

Moving on to step 9:
661 can be fit into 5780 8 times, resulting in a remainder of 492.
Write down 8 as next digit of the result. 
Result so far: 126381.8
Deduct 5288 from 5780 and we're left with 492.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4920, and continue the process.

Let's proceed to step 10:
The number 661 fits into 4920 7 times, leaving a remainder of 293.
Record the quotient 7 as the next digit in the result. 
Result so far: 126381.87
The remainder is 293 after subtracting 4627 from 4920.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2930, and continue the process.

Going ahead to step 11:
If we divide 2930 by 661, we get 4 and a remainder of 286.
Put 4 as the next digit of the answer. 
Result so far: 126381.874
Subtract 2644 from 2930 to get 286.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2860, and continue the process.

Step 12:
When dividing 2860 by 661, we get 4 with a remainder of 216.
Use 4 as the next digit of our solution. 
Result so far: 126381.8744
Subtract 2644 from 2860 to get 216.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2160, and continue the process.

The final outcome is 126381.8744, with a leftover of 0.00216.