686478 ÷ 42 
We're looking to find how many times 42 goes into 686478.

On to step 1:
When dividing 6 by 42, we get 0 with a remainder of 6.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 6 to get 6.
Grab the next digit (8) from the dividend, add it to 6, then carry on: 68 / 42

Advancing to step 2:
68 divided by 42 is 1 with a remainder of 26.
The next digit of our result is 1. 
Result so far: 1.0
The remainder is 26 after subtracting 42 from 68.
Include the next digit (6) from the dividend after 26, then repeat: 266 / 42

Let's proceed to step 3:
If we divide 266 by 42, we get 6 and a remainder of 14.
The number 6 becomes the next digit in our result. 
Result so far: 16.0
The remainder is 14 after subtracting 252 from 266.
Bring next digit (4) of the dividend behind the 14 and repeat the process: 144 / 42

On to step 4:
When dividing 144 by 42, we get 3 with a remainder of 18.
Use 3 as the next digit of our solution. 
Result so far: 163.0
Subtract 126 from 144 to get 18.
Grab the next digit (7) from the dividend, add it to 18, then carry on: 187 / 42

Let's proceed to step 5:
42 can be fit into 187 4 times, resulting in a remainder of 19.
Put 4 as the next digit of the answer. 
Result so far: 1634.0
The remainder is 19 after subtracting 168 from 187.
Take the next digit (8) from the dividend and append it to 19, then repeat: 198 / 42

Going ahead to step 6:
198 divided by 42 is 4 with a remainder of 30.
The number 4 becomes the next digit in our result. 
Result so far: 16344.0
Subtracting 168 from 198 leaves us with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Step 7:
The number 42 fits into 300 7 times, leaving a remainder of 6.
Use 7 as the next digit of our solution. 
Result so far: 16344.7
Subtract 294 from 300 to 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.

Step 8:
When dividing 60 by 42, we get 1 with a remainder of 18.
The number 1 becomes the next digit in our result. 
Result so far: 16344.71
Subtract 42 from 60 to get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Going ahead to step 9:
If we divide 180 by 42, we get 4 and a remainder of 12.
Record the quotient 4 as the next digit in the result. 
Result so far: 16344.714
Subtracting 168 from 180 leaves us with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Step 10:
42 can be fit into 120 2 times, resulting in a remainder of 36.
Use 2 as the next digit of our solution. 
Result so far: 16344.7142
If we subtract 84 from 120, we get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Step 11:
42 goes into 360 8 times with a remainder of 24.
The next digit of our result is 8. 
Result so far: 16344.71428
If we subtract 336 from 360, we get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Let's proceed to step 12:
If we divide 240 by 42, we get 5 and a remainder of 30.
Use 5 as the next digit of our solution. 
Result so far: 16344.714285
Subtract 210 from 240 to get 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

Advancing to step 13:
42 goes into 300 7 times with a remainder of 6.
The next digit of our result is 7. 
Result so far: 16344.7142857
If we subtract 294 from 300, 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.

Let's proceed to step 14:
42 can be fit into 60 1 times, resulting in a remainder of 18.
Put 1 as the next digit of the answer. 
Result so far: 16344.71428571
The remainder is 18 after subtracting 42 from 60.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

After the division, we end up with 16344.71428571 and a remainder of 1.8e-08.