66485523 ÷ 405 
The aim is to understand the frequency of 405 in 66485523.

Step 1:
6 divided by 405 is 0 with a remainder of 6.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Take the next digit (6) from the dividend and append it to 6, then repeat: 66 / 405

Let's proceed to step 2:
405 can be fit into 66 0 times, resulting in a remainder of 66.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 66 after subtracting 0 from 66.
Fetch the next digit (4) from the dividend, attach it to 66 and continue: 664 / 405

Moving on to step 3:
405 can be fit into 664 1 times, resulting in a remainder of 259.
Use 1 as the next digit of our solution. 
Result so far: 1.0
If we take 405 away from 664, we end up with 259.
Append the next digit (8) from the dividend to 259 and continue with: 2598 / 405

Advancing to step 4:
405 goes into 2598 6 times with a remainder of 168.
Put 6 as the next digit of the answer. 
Result so far: 16.0
Subtract 2430 from 2598 to get 168.
Grab the next digit (5) from the dividend, add it to 168, then carry on: 1685 / 405

Advancing to step 5:
1685 divided by 405 is 4 with a remainder of 65.
Write down 4 as next digit of the result. 
Result so far: 164.0
Subtract 1620 from 1685 to get 65.
Take the next digit (5) from the dividend and append it to 65, then repeat: 655 / 405

Let's proceed to step 6:
655 divided by 405 is 1 with a remainder of 250.
Write down 1 as next digit of the result. 
Result so far: 1641.0
If we take 405 away from 655, we end up with 250.
Bring next digit (2) of the dividend behind the 250 and repeat the process: 2502 / 405

Going ahead to step 7:
405 goes into 2502 6 times with a remainder of 72.
The number 6 becomes the next digit in our result. 
Result so far: 16416.0
If we subtract 2430 from 2502, we get 72.
Grab the next digit (3) from the dividend, add it to 72, then carry on: 723 / 405

Let's proceed to step 8:
When dividing 723 by 405, we get 1 with a remainder of 318.
Put 1 as the next digit of the answer. 
Result so far: 164161.0
If we take 405 away from 723, we end up with 318.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3180, and continue the process.

Moving on to step 9:
405 can be fit into 3180 7 times, resulting in a remainder of 345.
The next digit of our result is 7. 
Result so far: 164161.7
Subtract 2835 from 3180 to get 345.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3450, and continue the process.

Moving on to step 10:
3450 divided by 405 is 8 with a remainder of 210.
Use 8 as the next digit of our solution. 
Result so far: 164161.78
If we subtract 3240 from 3450, we get 210.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2100, and continue the process.

Advancing to step 11:
405 goes into 2100 5 times with a remainder of 75.
Put 5 as the next digit of the answer. 
Result so far: 164161.785
Subtract 2025 from 2100 to get 75.
Since there are no more digits in the dividend, we add a zero to the remainder making it 750, and continue the process.

On to step 12:
When dividing 750 by 405, we get 1 with a remainder of 345.
Record the quotient 1 as the next digit in the result. 
Result so far: 164161.7851
The remainder is 345 after subtracting 405 from 750.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3450, and continue the process.

Moving on to step 13:
405 can be fit into 3450 8 times, resulting in a remainder of 210.
The next digit of our result is 8. 
Result so far: 164161.78518
If we subtract 3240 from 3450, we get 210.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2100, and continue the process.

Step 14:
If we divide 2100 by 405, we get 5 and a remainder of 75.
The number 5 becomes the next digit in our result. 
Result so far: 164161.785185
Subtract 2025 from 2100 to get 75.
Since there are no more digits in the dividend, we add a zero to the remainder making it 750, and continue the process.

On to step 15:
If we divide 750 by 405, we get 1 and a remainder of 345.
Record the quotient 1 as the next digit in the result. 
Result so far: 164161.7851851
Subtracting 405 from 750 leaves us with 345.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3450, and continue the process.

Moving on to step 16:
3450 divided by 405 is 8 with a remainder of 210.
The number 8 becomes the next digit in our result. 
Result so far: 164161.78518518
Deduct 3240 from 3450 and we're left with 210.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2100, and continue the process.

The quotient of the division is 164161.78518518, and the remainder is 2.1e-07.