Let's divide 12640422 by 421
We want to figure out the number of times 12640422 can be divided by 421.

Step 1:
The number 421 fits into 1 0 times, leaving a remainder of 1.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 1 to get 1.
Fetch the next digit (2) from the dividend, attach it to 1 and continue: 12 / 421

Step 2:
421 can be fit into 12 0 times, resulting in a remainder of 12.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 12, we get 12.
Include the next digit (6) from the dividend after 12, then repeat: 126 / 421

On to step 3:
When dividing 126 by 421, we get 0 with a remainder of 126.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 126 to get 126.
Fetch the next digit (4) from the dividend, attach it to 126 and continue: 1264 / 421

Advancing to step 4:
421 goes into 1264 3 times with a remainder of 1.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
Deduct 1263 from 1264 and we're left with 1.
Grab the next digit (0) from the dividend, add it to 1, then carry on: 10 / 421

Advancing to step 5:
If we divide 10 by 421, we get 0 and a remainder of 10.
Use 0 as the next digit of our solution. 
Result so far: 30.0
The remainder is 10 after subtracting 0 from 10.
Take the next digit (4) from the dividend and append it to 10, then repeat: 104 / 421

Advancing to step 6:
104 divided by 421 is 0 with a remainder of 104.
Record the quotient 0 as the next digit in the result. 
Result so far: 300.0
If we subtract 0 from 104, we get 104.
Grab the next digit (2) from the dividend, add it to 104, then carry on: 1042 / 421

Going ahead to step 7:
The number 421 fits into 1042 2 times, leaving a remainder of 200.
Use 2 as the next digit of our solution. 
Result so far: 3002.0
Deduct 842 from 1042 and we're left with 200.
Fetch the next digit (2) from the dividend, attach it to 200 and continue: 2002 / 421

Let's proceed to step 8:
421 can be fit into 2002 4 times, resulting in a remainder of 318.
Write down 4 as next digit of the result. 
Result so far: 30024.0
If we take 1684 away from 2002, we end up with 318.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3180, and continue the process.

Advancing to step 9:
3180 divided by 421 is 7 with a remainder of 233.
Record the quotient 7 as the next digit in the result. 
Result so far: 30024.7
Subtract 2947 from 3180 to get 233.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2330, and continue the process.

Step 10:
If we divide 2330 by 421, we get 5 and a remainder of 225.
The next digit of our result is 5. 
Result so far: 30024.75
If we take 2105 away from 2330, we end up 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.

Going ahead to step 11:
421 goes into 2250 5 times with a remainder of 145.
Record the quotient 5 as the next digit in the result. 
Result so far: 30024.755
If we subtract 2105 from 2250, we get 145.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1450, and continue the process.

After the division, we end up with 30024.755 and a remainder of 0.0145.