13801023 divided by 645 
Our goal is to divide 13801023 by 645.

Step 1:
645 goes into 1 0 times with a remainder of 1.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 1 leaves us with 1.
Include the next digit (3) from the dividend after 1, then repeat: 13 / 645

Moving on to step 2:
645 goes into 13 0 times with a remainder of 13.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 13, we get 13.
Take the next digit (8) from the dividend and append it to 13, then repeat: 138 / 645

Going ahead to step 3:
If we divide 138 by 645, we get 0 and a remainder of 138.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 138 after subtracting 0 from 138.
Bring next digit (0) of the dividend behind the 138 and repeat the process: 1380 / 645

Moving on to step 4:
645 goes into 1380 2 times with a remainder of 90.
The number 2 becomes the next digit in our result. 
Result so far: 2.0
Deduct 1290 from 1380 and we're left with 90.
Take the next digit (1) from the dividend and append it to 90, then repeat: 901 / 645

On to step 5:
901 divided by 645 is 1 with a remainder of 256.
The next digit of our result is 1. 
Result so far: 21.0
If we subtract 645 from 901, we get 256.
Grab the next digit (0) from the dividend, add it to 256, then carry on: 2560 / 645

Moving on to step 6:
If we divide 2560 by 645, we get 3 and a remainder of 625.
Use 3 as the next digit of our solution. 
Result so far: 213.0
If we take 1935 away from 2560, we end up with 625.
Append the next digit (2) from the dividend to 625 and continue with: 6252 / 645

Step 7:
645 goes into 6252 9 times with a remainder of 447.
Record the quotient 9 as the next digit in the result. 
Result so far: 2139.0
The remainder is 447 after subtracting 5805 from 6252.
Take the next digit (3) from the dividend and append it to 447, then repeat: 4473 / 645

Let's proceed to step 8:
4473 divided by 645 is 6 with a remainder of 603.
The next digit of our result is 6. 
Result so far: 21396.0
The remainder is 603 after subtracting 3870 from 4473.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6030, and continue the process.

Advancing to step 9:
645 goes into 6030 9 times with a remainder of 225.
Put 9 as the next digit of the answer. 
Result so far: 21396.9
Deduct 5805 from 6030 and we're left with 225.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2250, and continue the process.

Advancing to step 10:
645 can be fit into 2250 3 times, resulting in a remainder of 315.
The next digit of our result is 3. 
Result so far: 21396.93
The remainder is 315 after subtracting 1935 from 2250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3150, and continue the process.

On to step 11:
3150 divided by 645 is 4 with a remainder of 570.
Write down 4 as next digit of the result. 
Result so far: 21396.934
The remainder is 570 after subtracting 2580 from 3150.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5700, and continue the process.

Let's proceed to step 12:
5700 divided by 645 is 8 with a remainder of 540.
Use 8 as the next digit of our solution. 
Result so far: 21396.9348
If we subtract 5160 from 5700, we get 540.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5400, and continue the process.

Let's proceed to step 13:
645 goes into 5400 8 times with a remainder of 240.
Use 8 as the next digit of our solution. 
Result so far: 21396.93488
If we take 5160 away from 5400, we end up with 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2400, and continue the process.

After the division, we end up with 21396.93488 and a remainder of 0.00024.