We're dividing 53406023 by 645 
We're looking to find how many times 645 goes into 53406023.

Going ahead to step 1:
The number 645 fits into 5 0 times, leaving 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

On to step 2:
53 divided by 645 is 0 with a remainder of 53.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 53, we end up with 53.
Grab the next digit (4) from the dividend, add it to 53, then carry on: 534 / 645

Moving on to step 3:
When dividing 534 by 645, we get 0 with a remainder of 534.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we take 0 away from 534, we end up with 534.
Take the next digit (0) from the dividend and append it to 534, then repeat: 5340 / 645

Step 4:
If we divide 5340 by 645, we get 8 and a remainder of 180.
Record the quotient 8 as the next digit in the result. 
Result so far: 8.0
If we subtract 5160 from 5340, we get 180.
Take the next digit (6) from the dividend and append it to 180, then repeat: 1806 / 645

Advancing to step 5:
645 goes into 1806 2 times with a remainder of 516.
Use 2 as the next digit of our solution. 
Result so far: 82.0
If we subtract 1290 from 1806, we get 516.
Include the next digit (0) from the dividend after 516, then repeat: 5160 / 645

Moving on to step 6:
645 goes into 5160 8 times with a remainder of 0.
The next digit of our result is 8. 
Result so far: 828.0
Subtract 5160 from 5160 to get 0.
Include the next digit (2) from the dividend after 0, then repeat: 2 / 645

Advancing to step 7:
645 goes into 2 0 times with a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 8280.0
The remainder is 2 after subtracting 0 from 2.
Take the next digit (3) from the dividend and append it to 2, then repeat: 23 / 645

Step 8:
23 divided by 645 is 0 with a remainder of 23.
The next digit of our result is 0. 
Result so far: 82800.0
Subtracting 0 from 23 leaves us with 23.
Since there are no more digits in the dividend, we add a zero to the remainder making it 230, and continue the process.

Going ahead to step 9:
The number 645 fits into 230 0 times, leaving a remainder of 230.
The next digit of our result is 0. 
Result so far: 82800.0
Deduct 0 from 230 and we're left with 230.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2300, and continue the process.

Going ahead to step 10:
When dividing 2300 by 645, we get 3 with a remainder of 365.
The next digit of our result is 3. 
Result so far: 82800.03
If we subtract 1935 from 2300, we get 365.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3650, and continue the process.

Advancing to step 11:
When dividing 3650 by 645, we get 5 with a remainder of 425.
Use 5 as the next digit of our solution. 
Result so far: 82800.035
Subtracting 3225 from 3650 leaves us with 425.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4250, and continue the process.

Let's proceed to step 12:
If we divide 4250 by 645, we get 6 and a remainder of 380.
Put 6 as the next digit of the answer. 
Result so far: 82800.0356
The remainder is 380 after subtracting 3870 from 4250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3800, and continue the process.

Moving on to step 13:
3800 divided by 645 is 5 with a remainder of 575.
Put 5 as the next digit of the answer. 
Result so far: 82800.03565
If we subtract 3225 from 3800, we get 575.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5750, and continue the process.

Moving on to step 14:
645 goes into 5750 8 times with a remainder of 590.
The next digit of our result is 8. 
Result so far: 82800.035658
If we take 5160 away from 5750, we end up with 590.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5900, and continue the process.

On to step 15:
When dividing 5900 by 645, we get 9 with a remainder of 95.
Put 9 as the next digit of the answer. 
Result so far: 82800.0356589
If we subtract 5805 from 5900, we get 95.
Since there are no more digits in the dividend, we add a zero to the remainder making it 950, and continue the process.

Step 16:
The number 645 fits into 950 1 times, leaving a remainder of 305.
Use 1 as the next digit of our solution. 
Result so far: 82800.03565891
If we take 645 away from 950, we end up with 305.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3050, and continue the process.

The final outcome is 82800.03565891, with a leftover of 3.05e-07.