We look at the division of 53807803 by 645 
We want to divide 53807803 by 645.

Let's proceed to step 1:
When dividing 5 by 645, we get 0 with a remainder of 5.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 5 to get 5.
Fetch the next digit (3) from the dividend, attach it to 5 and continue: 53 / 645

Step 2:
When dividing 53 by 645, we get 0 with a remainder of 53.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtracting 0 from 53 leaves us with 53.
Bring next digit (8) of the dividend behind the 53 and repeat the process: 538 / 645

Going ahead to step 3:
645 can be fit into 538 0 times, resulting in a remainder of 538.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 538 leaves us with 538.
Grab the next digit (0) from the dividend, add it to 538, then carry on: 5380 / 645

Moving on to step 4:
When dividing 5380 by 645, we get 8 with a remainder of 220.
Record the quotient 8 as the next digit in the result. 
Result so far: 8.0
Subtract 5160 from 5380 to get 220.
Bring next digit (7) of the dividend behind the 220 and repeat the process: 2207 / 645

Moving on to step 5:
645 goes into 2207 3 times with a remainder of 272.
Put 3 as the next digit of the answer. 
Result so far: 83.0
Subtracting 1935 from 2207 leaves us with 272.
Take the next digit (8) from the dividend and append it to 272, then repeat: 2728 / 645

Advancing to step 6:
When dividing 2728 by 645, we get 4 with a remainder of 148.
Use 4 as the next digit of our solution. 
Result so far: 834.0
If we subtract 2580 from 2728, we get 148.
Include the next digit (0) from the dividend after 148, then repeat: 1480 / 645

Step 7:
The number 645 fits into 1480 2 times, leaving a remainder of 190.
Use 2 as the next digit of our solution. 
Result so far: 8342.0
Deduct 1290 from 1480 and we're left with 190.
Bring next digit (3) of the dividend behind the 190 and repeat the process: 1903 / 645

On to step 8:
645 can be fit into 1903 2 times, resulting in a remainder of 613.
Record the quotient 2 as the next digit in the result. 
Result so far: 83422.0
If we take 1290 away from 1903, we end up with 613.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6130, and continue the process.

Advancing to step 9:
645 goes into 6130 9 times with a remainder of 325.
The next digit of our result is 9. 
Result so far: 83422.9
Subtracting 5805 from 6130 leaves us with 325.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3250, and continue the process.

Let's proceed to step 10:
645 can be fit into 3250 5 times, resulting in a remainder of 25.
Put 5 as the next digit of the answer. 
Result so far: 83422.95
The remainder is 25 after subtracting 3225 from 3250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Step 11:
The number 645 fits into 250 0 times, leaving a remainder of 250.
The next digit of our result is 0. 
Result so far: 83422.95
The remainder is 250 after subtracting 0 from 250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2500, and continue the process.

Advancing to step 12:
2500 divided by 645 is 3 with a remainder of 565.
Record the quotient 3 as the next digit in the result. 
Result so far: 83422.9503
Subtracting 1935 from 2500 leaves us with 565.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5650, and continue the process.

On to step 13:
645 goes into 5650 8 times with a remainder of 490.
The next digit of our result is 8. 
Result so far: 83422.95038
If we subtract 5160 from 5650, we get 490.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4900, and continue the process.

Let's proceed to step 14:
When dividing 4900 by 645, we get 7 with a remainder of 385.
Record the quotient 7 as the next digit in the result. 
Result so far: 83422.950387
Subtract 4515 from 4900 to get 385.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3850, and continue the process.

Going ahead to step 15:
The number 645 fits into 3850 5 times, leaving a remainder of 625.
Write down 5 as next digit of the result. 
Result so far: 83422.9503875
The remainder is 625 after subtracting 3225 from 3850.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6250, and continue the process.

Step 16:
645 goes into 6250 9 times with a remainder of 445.
The number 9 becomes the next digit in our result. 
Result so far: 83422.95038759
If we subtract 5805 from 6250, we get 445.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4450, and continue the process.

After the division, we end up with 83422.95038759 and a remainder of 4.45e-07.