907123 ÷ 21 
Our goal is to divide 907123 by 21.

Let's proceed to step 1:
The number 21 fits into 9 0 times, leaving a remainder of 9.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 9 and we're left with 9.
Include the next digit (0) from the dividend after 9, then repeat: 90 / 21

Moving on to step 2:
90 divided by 21 is 4 with a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 4.0
Subtract 84 from 90 to get 6.
Bring next digit (7) of the dividend behind the 6 and repeat the process: 67 / 21

Let's proceed to step 3:
21 goes into 67 3 times with a remainder of 4.
Put 3 as the next digit of the answer. 
Result so far: 43.0
If we take 63 away from 67, we end up with 4.
Bring next digit (1) of the dividend behind the 4 and repeat the process: 41 / 21

Step 4:
21 goes into 41 1 times with a remainder of 20.
Write down 1 as next digit of the result. 
Result so far: 431.0
If we take 21 away from 41, we end up with 20.
Append the next digit (2) from the dividend to 20 and continue with: 202 / 21

Step 5:
21 can be fit into 202 9 times, resulting in a remainder of 13.
Put 9 as the next digit of the answer. 
Result so far: 4319.0
If we subtract 189 from 202, we get 13.
Fetch the next digit (3) from the dividend, attach it to 13 and continue: 133 / 21

Moving on to step 6:
When dividing 133 by 21, we get 6 with a remainder of 7.
Use 6 as the next digit of our solution. 
Result so far: 43196.0
If we subtract 126 from 133, we get 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Going ahead to step 7:
When dividing 70 by 21, we get 3 with a remainder of 7.
Use 3 as the next digit of our solution. 
Result so far: 43196.3
If we take 63 away from 70, we end up with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

Moving on to step 8:
21 goes into 70 3 times with a remainder of 7.
Put 3 as the next digit of the answer. 
Result so far: 43196.33
Subtracting 63 from 70 leaves us with 7.
Since there are no more digits in the dividend, we add a zero to the remainder making it 70, and continue the process.

The quotient of the division is 43196.33, and the remainder is 0.007.