66858469 ÷ 123 
We want to divide 66858469 by 123.

On to step 1:
If we divide 6 by 123, we get 0 and a remainder of 6.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 6 and we're left with 6.
Include the next digit (6) from the dividend after 6, then repeat: 66 / 123

Step 2:
66 divided by 123 is 0 with a remainder of 66.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 66 after subtracting 0 from 66.
Take the next digit (8) from the dividend and append it to 66, then repeat: 668 / 123

Let's proceed to step 3:
The number 123 fits into 668 5 times, leaving a remainder of 53.
The next digit of our result is 5. 
Result so far: 5.0
If we subtract 615 from 668, we get 53.
Bring next digit (5) of the dividend behind the 53 and repeat the process: 535 / 123

On to step 4:
If we divide 535 by 123, we get 4 and a remainder of 43.
Write down 4 as next digit of the result. 
Result so far: 54.0
The remainder is 43 after subtracting 492 from 535.
Fetch the next digit (8) from the dividend, attach it to 43 and continue: 438 / 123

On to step 5:
438 divided by 123 is 3 with a remainder of 69.
Record the quotient 3 as the next digit in the result. 
Result so far: 543.0
If we subtract 369 from 438, we get 69.
Include the next digit (4) from the dividend after 69, then repeat: 694 / 123

Moving on to step 6:
If we divide 694 by 123, we get 5 and a remainder of 79.
Record the quotient 5 as the next digit in the result. 
Result so far: 5435.0
Deduct 615 from 694 and we're left with 79.
Take the next digit (6) from the dividend and append it to 79, then repeat: 796 / 123

Going ahead to step 7:
796 divided by 123 is 6 with a remainder of 58.
Use 6 as the next digit of our solution. 
Result so far: 54356.0
If we subtract 738 from 796, we get 58.
Include the next digit (9) from the dividend after 58, then repeat: 589 / 123

On to step 8:
When dividing 589 by 123, we get 4 with a remainder of 97.
The number 4 becomes the next digit in our result. 
Result so far: 543564.0
Subtract 492 from 589 to get 97.
Since there are no more digits in the dividend, we add a zero to the remainder making it 970, and continue the process.

Advancing to step 9:
The number 123 fits into 970 7 times, leaving a remainder of 109.
The number 7 becomes the next digit in our result. 
Result so far: 543564.7
If we take 861 away from 970, we end up with 109.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1090, and continue the process.

Step 10:
1090 divided by 123 is 8 with a remainder of 106.
The next digit of our result is 8. 
Result so far: 543564.78
Deduct 984 from 1090 and we're left with 106.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1060, and continue the process.

On to step 11:
If we divide 1060 by 123, we get 8 and a remainder of 76.
Write down 8 as next digit of the result. 
Result so far: 543564.788
If we subtract 984 from 1060, we get 76.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

In conclusion, the division gives 543564.788 with a balance of 0.0076.