Let's divide 12258434 by 420
We want to figure out the number of times 12258434 can be divided by 420.

Moving on to step 1:
420 goes into 1 0 times with a remainder of 1.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 1 and we're left with 1.
Append the next digit (2) from the dividend to 1 and continue with: 12 / 420

Step 2:
12 divided by 420 is 0 with a remainder of 12.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtract 0 from 12 to get 12.
Bring next digit (2) of the dividend behind the 12 and repeat the process: 122 / 420

Going ahead to step 3:
420 can be fit into 122 0 times, resulting in a remainder of 122.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Subtracting 0 from 122 leaves us with 122.
Fetch the next digit (5) from the dividend, attach it to 122 and continue: 1225 / 420

On to step 4:
1225 divided by 420 is 2 with a remainder of 385.
The next digit of our result is 2. 
Result so far: 2.0
The remainder is 385 after subtracting 840 from 1225.
Fetch the next digit (8) from the dividend, attach it to 385 and continue: 3858 / 420

Step 5:
420 goes into 3858 9 times with a remainder of 78.
Use 9 as the next digit of our solution. 
Result so far: 29.0
Deduct 3780 from 3858 and we're left with 78.
Take the next digit (4) from the dividend and append it to 78, then repeat: 784 / 420

Moving on to step 6:
784 divided by 420 is 1 with a remainder of 364.
Use 1 as the next digit of our solution. 
Result so far: 291.0
The remainder is 364 after subtracting 420 from 784.
Include the next digit (3) from the dividend after 364, then repeat: 3643 / 420

Moving on to step 7:
If we divide 3643 by 420, we get 8 and a remainder of 283.
Put 8 as the next digit of the answer. 
Result so far: 2918.0
Subtract 3360 from 3643 to get 283.
Append the next digit (4) from the dividend to 283 and continue with: 2834 / 420

Let's proceed to step 8:
If we divide 2834 by 420, we get 6 and a remainder of 314.
The number 6 becomes the next digit in our result. 
Result so far: 29186.0
If we subtract 2520 from 2834, we get 314.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3140, and continue the process.

Moving on to step 9:
When dividing 3140 by 420, we get 7 with a remainder of 200.
The next digit of our result is 7. 
Result so far: 29186.7
The remainder is 200 after subtracting 2940 from 3140.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2000, and continue the process.

Step 10:
The number 420 fits into 2000 4 times, leaving a remainder of 320.
Write down 4 as next digit of the result. 
Result so far: 29186.74
Subtract 1680 from 2000 to get 320.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3200, and continue the process.

Going ahead to step 11:
If we divide 3200 by 420, we get 7 and a remainder of 260.
Write down 7 as next digit of the result. 
Result so far: 29186.747
Deduct 2940 from 3200 and we're left with 260.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2600, and continue the process.

On to step 12:
The number 420 fits into 2600 6 times, leaving a remainder of 80.
Use 6 as the next digit of our solution. 
Result so far: 29186.7476
Deduct 2520 from 2600 and we're left with 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 800, and continue the process.

Moving on to step 13:
When dividing 800 by 420, we get 1 with a remainder of 380.
The number 1 becomes the next digit in our result. 
Result so far: 29186.74761
If we subtract 420 from 800, we get 380.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3800, and continue the process.

Let's proceed to step 14:
3800 divided by 420 is 9 with a remainder of 20.
Record the quotient 9 as the next digit in the result. 
Result so far: 29186.747619
If we subtract 3780 from 3800, we get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Going ahead to step 15:
If we divide 200 by 420, we get 0 and a remainder of 200.
Use 0 as the next digit of our solution. 
Result so far: 29186.747619
Subtract 0 from 200 to get 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2000, and continue the process.

Let's proceed to step 16:
The number 420 fits into 2000 4 times, leaving a remainder of 320.
Record the quotient 4 as the next digit in the result. 
Result so far: 29186.74761904
If we take 1680 away from 2000, we end up with 320.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3200, and continue the process.

The final result is 29186.74761904 with a remainder of 3.2e-07.