20405689 divided by 129 
We want to divide 20405689 by 129.

Advancing to step 1:
When dividing 2 by 129, we get 0 with a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Append the next digit (0) from the dividend to 2 and continue with: 20 / 129

Let's proceed to step 2:
129 goes into 20 0 times with a remainder of 20.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 20 to get 20.
Grab the next digit (4) from the dividend, add it to 20, then carry on: 204 / 129

Let's proceed to step 3:
When dividing 204 by 129, we get 1 with a remainder of 75.
Use 1 as the next digit of our solution. 
Result so far: 1.0
Subtract 129 from 204 to get 75.
Append the next digit (0) from the dividend to 75 and continue with: 750 / 129

Let's proceed to step 4:
When dividing 750 by 129, we get 5 with a remainder of 105.
Record the quotient 5 as the next digit in the result. 
Result so far: 15.0
If we take 645 away from 750, we end up with 105.
Append the next digit (5) from the dividend to 105 and continue with: 1055 / 129

Step 5:
If we divide 1055 by 129, we get 8 and a remainder of 23.
Put 8 as the next digit of the answer. 
Result so far: 158.0
If we take 1032 away from 1055, we end up with 23.
Bring next digit (6) of the dividend behind the 23 and repeat the process: 236 / 129

Let's proceed to step 6:
If we divide 236 by 129, we get 1 and a remainder of 107.
The next digit of our result is 1. 
Result so far: 1581.0
If we take 129 away from 236, we end up with 107.
Append the next digit (8) from the dividend to 107 and continue with: 1078 / 129

Going ahead to step 7:
1078 divided by 129 is 8 with a remainder of 46.
Use 8 as the next digit of our solution. 
Result so far: 15818.0
Subtracting 1032 from 1078 leaves us with 46.
Grab the next digit (9) from the dividend, add it to 46, then carry on: 469 / 129

Let's proceed to step 8:
If we divide 469 by 129, we get 3 and a remainder of 82.
Record the quotient 3 as the next digit in the result. 
Result so far: 158183.0
If we take 387 away from 469, we end up with 82.
Since there are no more digits in the dividend, we add a zero to the remainder making it 820, and continue the process.

On to step 9:
129 can be fit into 820 6 times, resulting in a remainder of 46.
The next digit of our result is 6. 
Result so far: 158183.6
The remainder is 46 after subtracting 774 from 820.
Since there are no more digits in the dividend, we add a zero to the remainder making it 460, and continue the process.

Let's proceed to step 10:
129 can be fit into 460 3 times, resulting in a remainder of 73.
The number 3 becomes the next digit in our result. 
Result so far: 158183.63
If we subtract 387 from 460, we get 73.
Since there are no more digits in the dividend, we add a zero to the remainder making it 730, and continue the process.

Step 11:
129 can be fit into 730 5 times, resulting in a remainder of 85.
Write down 5 as next digit of the result. 
Result so far: 158183.635
Deduct 645 from 730 and we're left with 85.
Since there are no more digits in the dividend, we add a zero to the remainder making it 850, and continue the process.

Let's proceed to step 12:
850 divided by 129 is 6 with a remainder of 76.
The next digit of our result is 6. 
Result so far: 158183.6356
If we subtract 774 from 850, we get 76.
Since there are no more digits in the dividend, we add a zero to the remainder making it 760, and continue the process.

Advancing to step 13:
129 goes into 760 5 times with a remainder of 115.
The number 5 becomes the next digit in our result. 
Result so far: 158183.63565
Subtracting 645 from 760 leaves us with 115.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1150, and continue the process.

On to step 14:
129 goes into 1150 8 times with a remainder of 118.
Put 8 as the next digit of the answer. 
Result so far: 158183.635658
If we take 1032 away from 1150, we end up with 118.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1180, and continue the process.

Step 15:
When dividing 1180 by 129, we get 9 with a remainder of 19.
Record the quotient 9 as the next digit in the result. 
Result so far: 158183.6356589
If we subtract 1161 from 1180, we get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Moving on to step 16:
129 can be fit into 190 1 times, resulting in a remainder of 61.
The next digit of our result is 1. 
Result so far: 158183.63565891
The remainder is 61 after subtracting 129 from 190.
Since there are no more digits in the dividend, we add a zero to the remainder making it 610, and continue the process.

The final outcome is 158183.63565891, with a leftover of 6.1e-08.