66560619 ÷ 399 
Let's see how many times 399 fits into 66560619.

Let's proceed to step 1:
When dividing 6 by 399, we get 0 with a remainder of 6.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 399

Going ahead to step 2:
The number 399 fits into 66 0 times, leaving a remainder of 66.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 66, we get 66.
Take the next digit (5) from the dividend and append it to 66, then repeat: 665 / 399

Let's proceed to step 3:
399 can be fit into 665 1 times, resulting in a remainder of 266.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Deduct 399 from 665 and we're left with 266.
Bring next digit (6) of the dividend behind the 266 and repeat the process: 2666 / 399

Advancing to step 4:
2666 divided by 399 is 6 with a remainder of 272.
The next digit of our result is 6. 
Result so far: 16.0
If we subtract 2394 from 2666, we get 272.
Fetch the next digit (0) from the dividend, attach it to 272 and continue: 2720 / 399

Advancing to step 5:
If we divide 2720 by 399, we get 6 and a remainder of 326.
The number 6 becomes the next digit in our result. 
Result so far: 166.0
Deduct 2394 from 2720 and we're left with 326.
Take the next digit (6) from the dividend and append it to 326, then repeat: 3266 / 399

Let's proceed to step 6:
399 goes into 3266 8 times with a remainder of 74.
Write down 8 as next digit of the result. 
Result so far: 1668.0
Deduct 3192 from 3266 and we're left with 74.
Bring next digit (1) of the dividend behind the 74 and repeat the process: 741 / 399

Going ahead to step 7:
When dividing 741 by 399, we get 1 with a remainder of 342.
Put 1 as the next digit of the answer. 
Result so far: 16681.0
Subtracting 399 from 741 leaves us with 342.
Bring next digit (9) of the dividend behind the 342 and repeat the process: 3429 / 399

On to step 8:
3429 divided by 399 is 8 with a remainder of 237.
Use 8 as the next digit of our solution. 
Result so far: 166818.0
Subtracting 3192 from 3429 leaves us with 237.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2370, and continue the process.

Step 9:
The number 399 fits into 2370 5 times, leaving a remainder of 375.
Record the quotient 5 as the next digit in the result. 
Result so far: 166818.5
If we take 1995 away from 2370, we end up with 375.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3750, and continue the process.

Step 10:
399 goes into 3750 9 times with a remainder of 159.
The number 9 becomes the next digit in our result. 
Result so far: 166818.59
If we subtract 3591 from 3750, we get 159.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1590, and continue the process.

Let's proceed to step 11:
If we divide 1590 by 399, we get 3 and a remainder of 393.
The number 3 becomes the next digit in our result. 
Result so far: 166818.593
Deduct 1197 from 1590 and we're left with 393.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3930, and continue the process.

Step 12:
399 goes into 3930 9 times with a remainder of 339.
Put 9 as the next digit of the answer. 
Result so far: 166818.5939
Subtracting 3591 from 3930 leaves us with 339.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3390, and continue the process.

Moving on to step 13:
399 can be fit into 3390 8 times, resulting in a remainder of 198.
Record the quotient 8 as the next digit in the result. 
Result so far: 166818.59398
If we subtract 3192 from 3390, we get 198.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1980, and continue the process.

Let's proceed to step 14:
If we divide 1980 by 399, we get 4 and a remainder of 384.
Use 4 as the next digit of our solution. 
Result so far: 166818.593984
If we take 1596 away from 1980, we end up with 384.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3840, and continue the process.

Going ahead to step 15:
When dividing 3840 by 399, we get 9 with a remainder of 249.
Write down 9 as next digit of the result. 
Result so far: 166818.5939849
Subtract 3591 from 3840 to get 249.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2490, and continue the process.

Let's proceed to step 16:
2490 divided by 399 is 6 with a remainder of 96.
Put 6 as the next digit of the answer. 
Result so far: 166818.59398496
Deduct 2394 from 2490 and we're left with 96.
Since there are no more digits in the dividend, we add a zero to the remainder making it 960, and continue the process.

In conclusion, the division gives 166818.59398496 with a balance of 9.6e-08.