We're dividing 42171487 by 645 
We're looking to find how many times 645 goes into 42171487.

On to step 1:
4 divided by 645 is 0 with a remainder of 4.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 4, we end up with 4.
Bring next digit (2) of the dividend behind the 4 and repeat the process: 42 / 645

On to step 2:
The number 645 fits into 42 0 times, leaving a remainder of 42.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
The remainder is 42 after subtracting 0 from 42.
Grab the next digit (1) from the dividend, add it to 42, then carry on: 421 / 645

Let's proceed to step 3:
When dividing 421 by 645, we get 0 with a remainder of 421.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 421, we end up with 421.
Include the next digit (7) from the dividend after 421, then repeat: 4217 / 645

Going ahead to step 4:
If we divide 4217 by 645, we get 6 and a remainder of 347.
Use 6 as the next digit of our solution. 
Result so far: 6.0
Subtracting 3870 from 4217 leaves us with 347.
Fetch the next digit (1) from the dividend, attach it to 347 and continue: 3471 / 645

Step 5:
If we divide 3471 by 645, we get 5 and a remainder of 246.
Write down 5 as next digit of the result. 
Result so far: 65.0
Deduct 3225 from 3471 and we're left with 246.
Bring next digit (4) of the dividend behind the 246 and repeat the process: 2464 / 645

Going ahead to step 6:
645 can be fit into 2464 3 times, resulting in a remainder of 529.
Put 3 as the next digit of the answer. 
Result so far: 653.0
Deduct 1935 from 2464 and we're left with 529.
Include the next digit (8) from the dividend after 529, then repeat: 5298 / 645

Step 7:
645 can be fit into 5298 8 times, resulting in a remainder of 138.
Use 8 as the next digit of our solution. 
Result so far: 6538.0
Subtract 5160 from 5298 to get 138.
Grab the next digit (7) from the dividend, add it to 138, then carry on: 1387 / 645

Moving on to step 8:
645 can be fit into 1387 2 times, resulting in a remainder of 97.
Use 2 as the next digit of our solution. 
Result so far: 65382.0
If we take 1290 away from 1387, we end up with 97.
Since there are no more digits in the dividend, we add a zero to the remainder making it 970, and continue the process.

Moving on to step 9:
970 divided by 645 is 1 with a remainder of 325.
Put 1 as the next digit of the answer. 
Result so far: 65382.1
Subtract 645 from 970 to get 325.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3250, and continue the process.

Going ahead to step 10:
3250 divided by 645 is 5 with a remainder of 25.
The number 5 becomes the next digit in our result. 
Result so far: 65382.15
If we subtract 3225 from 3250, we get 25.
Since there are no more digits in the dividend, we add a zero to the remainder making it 250, and continue the process.

Moving on to step 11:
The number 645 fits into 250 0 times, leaving a remainder of 250.
Record the quotient 0 as the next digit in the result. 
Result so far: 65382.15
If we subtract 0 from 250, we get 250.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2500, and continue the process.

On to step 12:
645 can be fit into 2500 3 times, resulting in a remainder of 565.
Record the quotient 3 as the next digit in the result. 
Result so far: 65382.1503
Subtract 1935 from 2500 to get 565.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5650, and continue the process.

Step 13:
5650 divided by 645 is 8 with a remainder of 490.
The next digit of our result is 8. 
Result so far: 65382.15038
Subtract 5160 from 5650 to 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.

On to step 14:
4900 divided by 645 is 7 with a remainder of 385.
Use 7 as the next digit of our solution. 
Result so far: 65382.150387
If we subtract 4515 from 4900, we 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:
3850 divided by 645 is 5 with a remainder of 625.
Record the quotient 5 as the next digit in the result. 
Result so far: 65382.1503875
Deduct 3225 from 3850 and we're left with 625.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6250, and continue the process.

On to step 16:
When dividing 6250 by 645, we get 9 with a remainder of 445.
Write down 9 as next digit of the result. 
Result so far: 65382.15038759
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.

The final outcome is 65382.15038759, with a leftover of 4.45e-07.