912103 ÷ 21 
We're looking to find how many times 21 goes into 912103.

Advancing to step 1:
The number 21 fits into 9 0 times, leaving a remainder of 9.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 9, we end up with 9.
Fetch the next digit (1) from the dividend, attach it to 9 and continue: 91 / 21

Advancing to step 2:
If we divide 91 by 21, we get 4 and a remainder of 7.
Write down 4 as next digit of the result. 
Result so far: 4.0
If we take 84 away from 91, we end up with 7.
Grab the next digit (2) from the dividend, add it to 7, then carry on: 72 / 21

Advancing to step 3:
If we divide 72 by 21, we get 3 and a remainder of 9.
Use 3 as the next digit of our solution. 
Result so far: 43.0
Subtract 63 from 72 to get 9.
Append the next digit (1) from the dividend to 9 and continue with: 91 / 21

On to step 4:
When dividing 91 by 21, we get 4 with a remainder of 7.
Use 4 as the next digit of our solution. 
Result so far: 434.0
If we take 84 away from 91, we end up with 7.
Take the next digit (0) from the dividend and append it to 7, then repeat: 70 / 21

Going ahead to step 5:
21 can be fit into 70 3 times, resulting in a remainder of 7.
The next digit of our result is 3. 
Result so far: 4343.0
Deduct 63 from 70 and we're left with 7.
Fetch the next digit (3) from the dividend, attach it to 7 and continue: 73 / 21

Moving on to step 6:
When dividing 73 by 21, we get 3 with a remainder of 10.
Use 3 as the next digit of our solution. 
Result so far: 43433.0
Subtract 63 from 73 to get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 7:
100 divided by 21 is 4 with a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 43433.4
If we subtract 84 from 100, we get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Let's proceed to step 8:
21 goes into 160 7 times with a remainder of 13.
The next digit of our result is 7. 
Result so far: 43433.47
If we take 147 away from 160, we end up with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Going ahead to step 9:
21 can be fit into 130 6 times, resulting in a remainder of 4.
The next digit of our result is 6. 
Result so far: 43433.476
If we take 126 away from 130, we end up with 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Step 10:
If we divide 40 by 21, we get 1 and a remainder of 19.
Use 1 as the next digit of our solution. 
Result so far: 43433.4761
If we take 21 away from 40, we end up with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

On to step 11:
21 can be fit into 190 9 times, resulting in a remainder of 1.
Write down 9 as next digit of the result. 
Result so far: 43433.47619
Subtract 189 from 190 to get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Advancing to step 12:
21 goes into 10 0 times with a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 43433.47619
Subtracting 0 from 10 leaves us with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 13:
21 can be fit into 100 4 times, resulting in a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 43433.4761904
Subtracting 84 from 100 leaves us with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 14:
21 can be fit into 160 7 times, resulting in a remainder of 13.
Write down 7 as next digit of the result. 
Result so far: 43433.47619047
Deduct 147 from 160 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

After the division, we end up with 43433.47619047 and a remainder of 1.3e-08.