309816 ÷ 87 
We want to divide 309816 by 87.

On to step 1:
87 can be fit into 3 0 times, resulting in a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we subtract 0 from 3, we get 3.
Append the next digit (0) from the dividend to 3 and continue with: 30 / 87

Moving on to step 2:
When dividing 30 by 87, we get 0 with a remainder of 30.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 30 to get 30.
Append the next digit (9) from the dividend to 30 and continue with: 309 / 87

Advancing to step 3:
309 divided by 87 is 3 with a remainder of 48.
The next digit of our result is 3. 
Result so far: 3.0
The remainder is 48 after subtracting 261 from 309.
Include the next digit (8) from the dividend after 48, then repeat: 488 / 87

On to step 4:
If we divide 488 by 87, we get 5 and a remainder of 53.
The number 5 becomes the next digit in our result. 
Result so far: 35.0
If we subtract 435 from 488, we get 53.
Bring next digit (1) of the dividend behind the 53 and repeat the process: 531 / 87

Step 5:
The number 87 fits into 531 6 times, leaving a remainder of 9.
Record the quotient 6 as the next digit in the result. 
Result so far: 356.0
If we subtract 522 from 531, we get 9.
Grab the next digit (6) from the dividend, add it to 9, then carry on: 96 / 87

Step 6:
The number 87 fits into 96 1 times, leaving a remainder of 9.
Put 1 as the next digit of the answer. 
Result so far: 3561.0
Deduct 87 from 96 and we're left with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

On to step 7:
When dividing 90 by 87, we get 1 with a remainder of 3.
Write down 1 as next digit of the result. 
Result so far: 3561.1
Deduct 87 from 90 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Going ahead to step 8:
If we divide 30 by 87, we get 0 and a remainder of 30.
The next digit of our result is 0. 
Result so far: 3561.1
If we subtract 0 from 30, we 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.

Moving on to step 9:
87 goes into 300 3 times with a remainder of 39.
Record the quotient 3 as the next digit in the result. 
Result so far: 3561.103
If we subtract 261 from 300, we get 39.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

On to step 10:
The number 87 fits into 390 4 times, leaving a remainder of 42.
Write down 4 as next digit of the result. 
Result so far: 3561.1034
Deduct 348 from 390 and we're left with 42.
Since there are no more digits in the dividend, we add a zero to the remainder making it 420, and continue the process.

Moving on to step 11:
When dividing 420 by 87, we get 4 with a remainder of 72.
The number 4 becomes the next digit in our result. 
Result so far: 3561.10344
If we take 348 away from 420, we end up with 72.
Since there are no more digits in the dividend, we add a zero to the remainder making it 720, and continue the process.

The final outcome is 3561.10344, with a leftover of 7.2e-05.