We divide 661940 by 13
The aim is to understand the frequency of 13 in 661940.

Advancing to step 1:
The number 13 fits into 6 0 times, leaving a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Grab the next digit (6) from the dividend, add it to 6, then carry on: 66 / 13

Step 2:
The number 13 fits into 66 5 times, leaving a remainder of 1.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
If we take 65 away from 66, we end up with 1.
Grab the next digit (1) from the dividend, add it to 1, then carry on: 11 / 13

Going ahead to step 3:
The number 13 fits into 11 0 times, leaving a remainder of 11.
Put 0 as the next digit of the answer. 
Result so far: 50.0
Deduct 0 from 11 and we're left with 11.
Take the next digit (9) from the dividend and append it to 11, then repeat: 119 / 13

Step 4:
119 divided by 13 is 9 with a remainder of 2.
The next digit of our result is 9. 
Result so far: 509.0
Deduct 117 from 119 and we're left with 2.
Fetch the next digit (4) from the dividend, attach it to 2 and continue: 24 / 13

Let's proceed to step 5:
13 goes into 24 1 times with a remainder of 11.
Record the quotient 1 as the next digit in the result. 
Result so far: 5091.0
If we subtract 13 from 24, we get 11.
Take the next digit (0) from the dividend and append it to 11, then repeat: 110 / 13

Step 6:
13 can be fit into 110 8 times, resulting in a remainder of 6.
The next digit of our result is 8. 
Result so far: 50918.0
Subtracting 104 from 110 leaves us 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.

Advancing to step 7:
60 divided by 13 is 4 with a remainder of 8.
The number 4 becomes the next digit in our result. 
Result so far: 50918.4
Subtracting 52 from 60 leaves us 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.

Step 8:
13 can be fit into 80 6 times, resulting in a remainder of 2.
The next digit of our result is 6. 
Result so far: 50918.46
The remainder is 2 after subtracting 78 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

On to step 9:
20 divided by 13 is 1 with a remainder of 7.
Write down 1 as next digit of the result. 
Result so far: 50918.461
Subtracting 13 from 20 leaves us with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Going ahead to step 10:
The number 13 fits into 70 5 times, leaving a remainder of 5.
Use 5 as the next digit of our solution. 
Result so far: 50918.4615
Subtract 65 from 70 to get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Step 11:
The number 13 fits into 50 3 times, leaving a remainder of 11.
Use 3 as the next digit of our solution. 
Result so far: 50918.46153
Subtract 39 from 50 to get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

On to step 12:
The number 13 fits into 110 8 times, leaving a remainder of 6.
The number 8 becomes the next digit in our result. 
Result so far: 50918.461538
If we subtract 104 from 110, we get 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

On to step 13:
13 can be fit into 60 4 times, resulting in a remainder of 8.
The next digit of our result is 4. 
Result so far: 50918.4615384
Subtracting 52 from 60 leaves us 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.

On to step 14:
13 goes into 80 6 times with a remainder of 2.
Record the quotient 6 as the next digit in the result. 
Result so far: 50918.46153846
If we subtract 78 from 80, we get 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Our division results in 50918.46153846 with a remaining 2e-09.