We're dividing 345123 by 87 
We want to divide 345123 by 87.

Step 1:
3 divided by 87 is 0 with a remainder of 3.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 3 to get 3.
Include the next digit (4) from the dividend after 3, then repeat: 34 / 87

Step 2:
If we divide 34 by 87, we get 0 and a remainder of 34.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 34 after subtracting 0 from 34.
Bring next digit (5) of the dividend behind the 34 and repeat the process: 345 / 87

Step 3:
When dividing 345 by 87, we get 3 with a remainder of 84.
Write down 3 as next digit of the result. 
Result so far: 3.0
The remainder is 84 after subtracting 261 from 345.
Grab the next digit (1) from the dividend, add it to 84, then carry on: 841 / 87

Step 4:
87 can be fit into 841 9 times, resulting in a remainder of 58.
Put 9 as the next digit of the answer. 
Result so far: 39.0
If we take 783 away from 841, we end up with 58.
Bring next digit (2) of the dividend behind the 58 and repeat the process: 582 / 87

Going ahead to step 5:
If we divide 582 by 87, we get 6 and a remainder of 60.
Write down 6 as next digit of the result. 
Result so far: 396.0
If we take 522 away from 582, we end up with 60.
Include the next digit (3) from the dividend after 60, then repeat: 603 / 87

Let's proceed to step 6:
87 goes into 603 6 times with a remainder of 81.
Use 6 as the next digit of our solution. 
Result so far: 3966.0
Deduct 522 from 603 and we're left with 81.
Since there are no more digits in the dividend, we add a zero to the remainder making it 810, and continue the process.

Advancing to step 7:
When dividing 810 by 87, we get 9 with a remainder of 27.
The number 9 becomes the next digit in our result. 
Result so far: 3966.9
If we take 783 away from 810, we end up with 27.
Since there are no more digits in the dividend, we add a zero to the remainder making it 270, and continue the process.

Advancing to step 8:
The number 87 fits into 270 3 times, leaving a remainder of 9.
Put 3 as the next digit of the answer. 
Result so far: 3966.93
If we take 261 away from 270, we end up 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.

Let's proceed to step 9:
87 goes into 90 1 times with a remainder of 3.
Put 1 as the next digit of the answer. 
Result so far: 3966.931
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.

On to step 10:
When dividing 30 by 87, we get 0 with a remainder of 30.
Put 0 as the next digit of the answer. 
Result so far: 3966.931
Subtract 0 from 30 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.

Moving on to step 11:
If we divide 300 by 87, we get 3 and a remainder of 39.
Write down 3 as next digit of the result. 
Result so far: 3966.93103
If we take 261 away from 300, we end up with 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 12:
The number 87 fits into 390 4 times, leaving a remainder of 42.
Record the quotient 4 as the next digit in the result. 
Result so far: 3966.931034
If we take 348 away from 390, we end up 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.

Advancing to step 13:
If we divide 420 by 87, we get 4 and a remainder of 72.
Put 4 as the next digit of the answer. 
Result so far: 3966.9310344
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.

After the division, we end up with 3966.9310344 and a remainder of 7.2e-07.