21153975 ÷ 321 
We're looking to find how many times 321 goes into 21153975.

Let's proceed to step 1:
The number 321 fits into 2 0 times, leaving a remainder of 2.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 321

Advancing to step 2:
21 divided by 321 is 0 with a remainder of 21.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 21 and we're left with 21.
Bring next digit (1) of the dividend behind the 21 and repeat the process: 211 / 321

Going ahead to step 3:
The number 321 fits into 211 0 times, leaving a remainder of 211.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 211 and we're left with 211.
Fetch the next digit (5) from the dividend, attach it to 211 and continue: 2115 / 321

Going ahead to step 4:
321 can be fit into 2115 6 times, resulting in a remainder of 189.
The number 6 becomes the next digit in our result. 
Result so far: 6.0
Deduct 1926 from 2115 and we're left with 189.
Fetch the next digit (3) from the dividend, attach it to 189 and continue: 1893 / 321

Moving on to step 5:
When dividing 1893 by 321, we get 5 with a remainder of 288.
Write down 5 as next digit of the result. 
Result so far: 65.0
Deduct 1605 from 1893 and we're left with 288.
Fetch the next digit (9) from the dividend, attach it to 288 and continue: 2889 / 321

Step 6:
If we divide 2889 by 321, we get 9 and a remainder of 0.
Record the quotient 9 as the next digit in the result. 
Result so far: 659.0
Subtract 2889 from 2889 to get 0.
Append the next digit (7) from the dividend to 0 and continue with: 7 / 321

Step 7:
If we divide 7 by 321, we get 0 and a remainder of 7.
Write down 0 as next digit of the result. 
Result so far: 6590.0
Deduct 0 from 7 and we're left with 7.
Include the next digit (5) from the dividend after 7, then repeat: 75 / 321

Let's proceed to step 8:
The number 321 fits into 75 0 times, leaving a remainder of 75.
Put 0 as the next digit of the answer. 
Result so far: 65900.0
Deduct 0 from 75 and we're left with 75.
Since there are no more digits in the dividend, we add a zero to the remainder making it 750, and continue the process.

Going ahead to step 9:
When dividing 750 by 321, we get 2 with a remainder of 108.
Put 2 as the next digit of the answer. 
Result so far: 65900.2
Deduct 642 from 750 and we're left with 108.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1080, and continue the process.

Going ahead to step 10:
The number 321 fits into 1080 3 times, leaving a remainder of 117.
Put 3 as the next digit of the answer. 
Result so far: 65900.23
The remainder is 117 after subtracting 963 from 1080.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1170, and continue the process.

Going ahead to step 11:
The number 321 fits into 1170 3 times, leaving a remainder of 207.
The number 3 becomes the next digit in our result. 
Result so far: 65900.233
Subtract 963 from 1170 to get 207.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2070, and continue the process.

Our division results in 65900.233 with a remaining 0.0207.