51215673 ÷ 869 
Our goal is to divide 51215673 by 869.

Step 1:
869 goes into 5 0 times with a remainder of 5.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 5 and we're left with 5.
Bring next digit (1) of the dividend behind the 5 and repeat the process: 51 / 869

Going ahead to step 2:
When dividing 51 by 869, we get 0 with a remainder of 51.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 51 leaves us with 51.
Include the next digit (2) from the dividend after 51, then repeat: 512 / 869

On to step 3:
The number 869 fits into 512 0 times, leaving a remainder of 512.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 512, we get 512.
Take the next digit (1) from the dividend and append it to 512, then repeat: 5121 / 869

Advancing to step 4:
The number 869 fits into 5121 5 times, leaving a remainder of 776.
Write down 5 as next digit of the result. 
Result so far: 5.0
Subtract 4345 from 5121 to get 776.
Include the next digit (5) from the dividend after 776, then repeat: 7765 / 869

Going ahead to step 5:
7765 divided by 869 is 8 with a remainder of 813.
Write down 8 as next digit of the result. 
Result so far: 58.0
The remainder is 813 after subtracting 6952 from 7765.
Append the next digit (6) from the dividend to 813 and continue with: 8136 / 869

Moving on to step 6:
When dividing 8136 by 869, we get 9 with a remainder of 315.
The number 9 becomes the next digit in our result. 
Result so far: 589.0
Deduct 7821 from 8136 and we're left with 315.
Grab the next digit (7) from the dividend, add it to 315, then carry on: 3157 / 869

Advancing to step 7:
The number 869 fits into 3157 3 times, leaving a remainder of 550.
The next digit of our result is 3. 
Result so far: 5893.0
If we subtract 2607 from 3157, we get 550.
Append the next digit (3) from the dividend to 550 and continue with: 5503 / 869

Advancing to step 8:
If we divide 5503 by 869, we get 6 and a remainder of 289.
Write down 6 as next digit of the result. 
Result so far: 58936.0
Deduct 5214 from 5503 and we're left with 289.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2890, and continue the process.

Advancing to step 9:
869 goes into 2890 3 times with a remainder of 283.
Write down 3 as next digit of the result. 
Result so far: 58936.3
Subtract 2607 from 2890 to get 283.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2830, and continue the process.

On to step 10:
869 can be fit into 2830 3 times, resulting in a remainder of 223.
Write down 3 as next digit of the result. 
Result so far: 58936.33
Subtracting 2607 from 2830 leaves us with 223.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2230, and continue the process.

The final outcome is 58936.33, with a leftover of 0.223.