We're dividing 51670371 by 129 
We want to divide 51670371 by 129.

On to step 1:
5 divided by 129 is 0 with a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Fetch the next digit (1) from the dividend, attach it to 5 and continue: 51 / 129

Moving on to step 2:
The number 129 fits into 51 0 times, leaving a remainder of 51.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 51 leaves us with 51.
Fetch the next digit (6) from the dividend, attach it to 51 and continue: 516 / 129

Moving on to step 3:
129 goes into 516 4 times with a remainder of 0.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
Deduct 516 from 516 and we're left with 0.
Append the next digit (7) from the dividend to 0 and continue with: 7 / 129

Going ahead to step 4:
7 divided by 129 is 0 with a remainder of 7.
The next digit of our result is 0. 
Result so far: 40.0
If we take 0 away from 7, we end up with 7.
Include the next digit (0) from the dividend after 7, then repeat: 70 / 129

Advancing to step 5:
129 can be fit into 70 0 times, resulting in a remainder of 70.
The next digit of our result is 0. 
Result so far: 400.0
The remainder is 70 after subtracting 0 from 70.
Fetch the next digit (3) from the dividend, attach it to 70 and continue: 703 / 129

On to step 6:
If we divide 703 by 129, we get 5 and a remainder of 58.
Put 5 as the next digit of the answer. 
Result so far: 4005.0
The remainder is 58 after subtracting 645 from 703.
Take the next digit (7) from the dividend and append it to 58, then repeat: 587 / 129

Let's proceed to step 7:
587 divided by 129 is 4 with a remainder of 71.
The next digit of our result is 4. 
Result so far: 40054.0
Subtracting 516 from 587 leaves us with 71.
Bring next digit (1) of the dividend behind the 71 and repeat the process: 711 / 129

Step 8:
129 goes into 711 5 times with a remainder of 66.
Record the quotient 5 as the next digit in the result. 
Result so far: 400545.0
The remainder is 66 after subtracting 645 from 711.
Since there are no more digits in the dividend, we add a zero to the remainder making it 660, and continue the process.

Moving on to step 9:
The number 129 fits into 660 5 times, leaving a remainder of 15.
Write down 5 as next digit of the result. 
Result so far: 400545.5
If we take 645 away from 660, we end up with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Step 10:
When dividing 150 by 129, we get 1 with a remainder of 21.
Record the quotient 1 as the next digit in the result. 
Result so far: 400545.51
Subtracting 129 from 150 leaves us with 21.
Since there are no more digits in the dividend, we add a zero to the remainder making it 210, and continue the process.

Step 11:
If we divide 210 by 129, we get 1 and a remainder of 81.
Record the quotient 1 as the next digit in the result. 
Result so far: 400545.511
The remainder is 81 after subtracting 129 from 210.
Since there are no more digits in the dividend, we add a zero to the remainder making it 810, and continue the process.

In conclusion, the division gives 400545.511 with a balance of 0.0081.