86173907 ÷ 129 
Let's see how many times 129 fits into 86173907.

On to step 1:
If we divide 8 by 129, we get 0 and a remainder of 8.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 8, we end up with 8.
Bring next digit (6) of the dividend behind the 8 and repeat the process: 86 / 129

Let's proceed to step 2:
129 can be fit into 86 0 times, resulting in a remainder of 86.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 86 to get 86.
Append the next digit (1) from the dividend to 86 and continue with: 861 / 129

Step 3:
129 goes into 861 6 times with a remainder of 87.
Write down 6 as next digit of the result. 
Result so far: 6.0
Deduct 774 from 861 and we're left with 87.
Bring next digit (7) of the dividend behind the 87 and repeat the process: 877 / 129

Going ahead to step 4:
129 can be fit into 877 6 times, resulting in a remainder of 103.
Put 6 as the next digit of the answer. 
Result so far: 66.0
The remainder is 103 after subtracting 774 from 877.
Fetch the next digit (3) from the dividend, attach it to 103 and continue: 1033 / 129

Moving on to step 5:
129 goes into 1033 8 times with a remainder of 1.
Write down 8 as next digit of the result. 
Result so far: 668.0
Deduct 1032 from 1033 and we're left with 1.
Fetch the next digit (9) from the dividend, attach it to 1 and continue: 19 / 129

Moving on to step 6:
When dividing 19 by 129, we get 0 with a remainder of 19.
Put 0 as the next digit of the answer. 
Result so far: 6680.0
Subtract 0 from 19 to get 19.
Grab the next digit (0) from the dividend, add it to 19, then carry on: 190 / 129

On to step 7:
The number 129 fits into 190 1 times, leaving a remainder of 61.
The number 1 becomes the next digit in our result. 
Result so far: 66801.0
If we subtract 129 from 190, we get 61.
Fetch the next digit (7) from the dividend, attach it to 61 and continue: 617 / 129

Let's proceed to step 8:
129 can be fit into 617 4 times, resulting in a remainder of 101.
The number 4 becomes the next digit in our result. 
Result so far: 668014.0
If we take 516 away from 617, we end up with 101.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1010, and continue the process.

Moving on to step 9:
If we divide 1010 by 129, we get 7 and a remainder of 107.
Put 7 as the next digit of the answer. 
Result so far: 668014.7
If we take 903 away from 1010, we end up with 107.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1070, and continue the process.

On to step 10:
129 goes into 1070 8 times with a remainder of 38.
Put 8 as the next digit of the answer. 
Result so far: 668014.78
If we subtract 1032 from 1070, we get 38.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

On to step 11:
129 goes into 380 2 times with a remainder of 122.
Put 2 as the next digit of the answer. 
Result so far: 668014.782
Subtract 258 from 380 to get 122.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1220, and continue the process.

Advancing to step 12:
When dividing 1220 by 129, we get 9 with a remainder of 59.
The next digit of our result is 9. 
Result so far: 668014.7829
The remainder is 59 after subtracting 1161 from 1220.
Since there are no more digits in the dividend, we add a zero to the remainder making it 590, and continue the process.

On to step 13:
590 divided by 129 is 4 with a remainder of 74.
The next digit of our result is 4. 
Result so far: 668014.78294
If we subtract 516 from 590, we get 74.
Since there are no more digits in the dividend, we add a zero to the remainder making it 740, and continue the process.

Advancing to step 14:
740 divided by 129 is 5 with a remainder of 95.
The next digit of our result is 5. 
Result so far: 668014.782945
If we take 645 away from 740, we end up with 95.
Since there are no more digits in the dividend, we add a zero to the remainder making it 950, and continue the process.

Going ahead to step 15:
The number 129 fits into 950 7 times, leaving a remainder of 47.
Put 7 as the next digit of the answer. 
Result so far: 668014.7829457
If we take 903 away from 950, we end up with 47.
Since there are no more digits in the dividend, we add a zero to the remainder making it 470, and continue the process.

Moving on to step 16:
If we divide 470 by 129, we get 3 and a remainder of 83.
The next digit of our result is 3. 
Result so far: 668014.78294573
Subtract 387 from 470 to get 83.
Since there are no more digits in the dividend, we add a zero to the remainder making it 830, and continue the process.

After the division, we end up with 668014.78294573 and a remainder of 8.3e-08.