870231 ÷ 51 
We're looking to find how many times 51 goes into 870231.

Step 1:
If we divide 8 by 51, we get 0 and a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 8 leaves us with 8.
Append the next digit (7) from the dividend to 8 and continue with: 87 / 51

Advancing to step 2:
The number 51 fits into 87 1 times, leaving a remainder of 36.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we subtract 51 from 87, we get 36.
Append the next digit (0) from the dividend to 36 and continue with: 360 / 51

Step 3:
360 divided by 51 is 7 with a remainder of 3.
The next digit of our result is 7. 
Result so far: 17.0
If we subtract 357 from 360, we get 3.
Fetch the next digit (2) from the dividend, attach it to 3 and continue: 32 / 51

On to step 4:
The number 51 fits into 32 0 times, leaving a remainder of 32.
The number 0 becomes the next digit in our result. 
Result so far: 170.0
If we subtract 0 from 32, we get 32.
Bring next digit (3) of the dividend behind the 32 and repeat the process: 323 / 51

Going ahead to step 5:
323 divided by 51 is 6 with a remainder of 17.
The number 6 becomes the next digit in our result. 
Result so far: 1706.0
If we subtract 306 from 323, we get 17.
Grab the next digit (1) from the dividend, add it to 17, then carry on: 171 / 51

Advancing to step 6:
51 goes into 171 3 times with a remainder of 18.
The next digit of our result is 3. 
Result so far: 17063.0
If we take 153 away from 171, we end up with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Advancing to step 7:
51 can be fit into 180 3 times, resulting in a remainder of 27.
The next digit of our result is 3. 
Result so far: 17063.3
The remainder is 27 after subtracting 153 from 180.
Since there are no more digits in the dividend, we add a zero to the remainder making it 270, and continue the process.

Moving on to step 8:
When dividing 270 by 51, we get 5 with a remainder of 15.
Record the quotient 5 as the next digit in the result. 
Result so far: 17063.35
The remainder is 15 after subtracting 255 from 270.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Step 9:
The number 51 fits into 150 2 times, leaving a remainder of 48.
Write down 2 as next digit of the result. 
Result so far: 17063.352
Subtract 102 from 150 to get 48.
Since there are no more digits in the dividend, we add a zero to the remainder making it 480, and continue the process.

On to step 10:
51 can be fit into 480 9 times, resulting in a remainder of 21.
Use 9 as the next digit of our solution. 
Result so far: 17063.3529
Subtract 459 from 480 to get 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

Advancing to step 11:
When dividing 210 by 51, we get 4 with a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 17063.35294
Subtract 204 from 210 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.

Going ahead to step 12:
If we divide 60 by 51, we get 1 and a remainder of 9.
Record the quotient 1 as the next digit in the result. 
Result so far: 17063.352941
Subtract 51 from 60 to get 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 13:
90 divided by 51 is 1 with a remainder of 39.
The next digit of our result is 1. 
Result so far: 17063.3529411
Deduct 51 from 90 and we're left 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.

The final outcome is 17063.3529411, with a leftover of 3.9e-07.