725991 ÷ 21 
We're looking to find how many times 21 goes into 725991.

Moving on to step 1:
When dividing 7 by 21, we get 0 with a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 7, we get 7.
Grab the next digit (2) from the dividend, add it to 7, then carry on: 72 / 21

Advancing to step 2:
The number 21 fits into 72 3 times, leaving a remainder of 9.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
The remainder is 9 after subtracting 63 from 72.
Bring next digit (5) of the dividend behind the 9 and repeat the process: 95 / 21

Moving on to step 3:
21 goes into 95 4 times with a remainder of 11.
Use 4 as the next digit of our solution. 
Result so far: 34.0
If we take 84 away from 95, we end up with 11.
Grab the next digit (9) from the dividend, add it to 11, then carry on: 119 / 21

Advancing to step 4:
The number 21 fits into 119 5 times, leaving a remainder of 14.
Put 5 as the next digit of the answer. 
Result so far: 345.0
Deduct 105 from 119 and we're left with 14.
Fetch the next digit (9) from the dividend, attach it to 14 and continue: 149 / 21

Moving on to step 5:
149 divided by 21 is 7 with a remainder of 2.
The next digit of our result is 7. 
Result so far: 3457.0
Subtract 147 from 149 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 21

Let's proceed to step 6:
When dividing 21 by 21, we get 1 with a remainder of 0.
Write down 1 as next digit of the result. 
Result so far: 34571.0
Subtract 21 from 21 to get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Advancing to step 7:
21 can be fit into 0 0 times, resulting in a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 34571.0
Deduct 0 from 0 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 8:
The number 21 fits into 0 0 times, leaving a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 34571.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final result is 34571.0 with a remainder of 0.0.