64253703 divided by 21 
Let's see how many times 21 fits into 64253703.

On to step 1:
6 divided by 21 is 0 with a remainder of 6.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Include the next digit (4) from the dividend after 6, then repeat: 64 / 21

Step 2:
64 divided by 21 is 3 with a remainder of 1.
Use 3 as the next digit of our solution. 
Result so far: 3.0
Subtracting 63 from 64 leaves us with 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 21

Moving on to step 3:
The number 21 fits into 12 0 times, leaving a remainder of 12.
The next digit of our result is 0. 
Result so far: 30.0
Deduct 0 from 12 and we're left with 12.
Bring next digit (5) of the dividend behind the 12 and repeat the process: 125 / 21

Moving on to step 4:
21 can be fit into 125 5 times, resulting in a remainder of 20.
The number 5 becomes the next digit in our result. 
Result so far: 305.0
If we subtract 105 from 125, we get 20.
Include the next digit (3) from the dividend after 20, then repeat: 203 / 21

Step 5:
The number 21 fits into 203 9 times, leaving a remainder of 14.
Write down 9 as next digit of the result. 
Result so far: 3059.0
Deduct 189 from 203 and we're left with 14.
Take the next digit (7) from the dividend and append it to 14, then repeat: 147 / 21

Let's proceed to step 6:
The number 21 fits into 147 7 times, leaving a remainder of 0.
Write down 7 as next digit of the result. 
Result so far: 30597.0
Subtract 147 from 147 to get 0.
Fetch the next digit (0) from the dividend, attach it to 0 and continue: 0 / 21

On to step 7:
When dividing 0 by 21, we get 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 305970.0
Deduct 0 from 0 and we're left with 0.
Include the next digit (3) from the dividend after 0, then repeat: 3 / 21

Going ahead to step 8:
The number 21 fits into 3 0 times, leaving a remainder of 3.
Put 0 as the next digit of the answer. 
Result so far: 3059700.0
The remainder is 3 after subtracting 0 from 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Step 9:
30 divided by 21 is 1 with a remainder of 9.
Use 1 as the next digit of our solution. 
Result so far: 3059700.1
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 10:
21 can be fit into 90 4 times, resulting in a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 3059700.14
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 11:
60 divided by 21 is 2 with a remainder of 18.
Write down 2 as next digit of the result. 
Result so far: 3059700.142
Subtracting 42 from 60 leaves us with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Going ahead to step 12:
180 divided by 21 is 8 with a remainder of 12.
Use 8 as the next digit of our solution. 
Result so far: 3059700.1428
Deduct 168 from 180 and we're left with 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Advancing to step 13:
The number 21 fits into 120 5 times, leaving a remainder of 15.
The next digit of our result is 5. 
Result so far: 3059700.14285
Subtract 105 from 120 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 14:
21 can be fit into 150 7 times, resulting in a remainder of 3.
The number 7 becomes the next digit in our result. 
Result so far: 3059700.142857
Subtracting 147 from 150 leaves us with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Moving on to step 15:
21 can be fit into 30 1 times, resulting in a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 3059700.1428571
Subtracting 21 from 30 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Going ahead to step 16:
If we divide 90 by 21, we get 4 and a remainder of 6.
The number 4 becomes the next digit in our result. 
Result so far: 3059700.14285714
The remainder is 6 after subtracting 84 from 90.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

The final outcome is 3059700.14285714, with a leftover of 6e-09.