We're dividing 143288 by 21 
We want to figure out the number of times 143288 can be divided by 21.

On to step 1:
When dividing 1 by 21, we get 0 with a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Bring next digit (4) of the dividend behind the 1 and repeat the process: 14 / 21

Moving on to step 2:
21 can be fit into 14 0 times, resulting in a remainder of 14.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 14 after subtracting 0 from 14.
Include the next digit (3) from the dividend after 14, then repeat: 143 / 21

Advancing to step 3:
If we divide 143 by 21, we get 6 and a remainder of 17.
Put 6 as the next digit of the answer. 
Result so far: 6.0
The remainder is 17 after subtracting 126 from 143.
Append the next digit (2) from the dividend to 17 and continue with: 172 / 21

On to step 4:
The number 21 fits into 172 8 times, leaving a remainder of 4.
Record the quotient 8 as the next digit in the result. 
Result so far: 68.0
Deduct 168 from 172 and we're left with 4.
Take the next digit (8) from the dividend and append it to 4, then repeat: 48 / 21

Let's proceed to step 5:
When dividing 48 by 21, we get 2 with a remainder of 6.
Use 2 as the next digit of our solution. 
Result so far: 682.0
Subtracting 42 from 48 leaves us with 6.
Fetch the next digit (8) from the dividend, attach it to 6 and continue: 68 / 21

Going ahead to step 6:
21 can be fit into 68 3 times, resulting in a remainder of 5.
Put 3 as the next digit of the answer. 
Result so far: 6823.0
Subtract 63 from 68 to get 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Let's proceed to step 7:
If we divide 50 by 21, we get 2 and a remainder of 8.
Record the quotient 2 as the next digit in the result. 
Result so far: 6823.2
If we take 42 away from 50, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Step 8:
21 goes into 80 3 times with a remainder of 17.
The next digit of our result is 3. 
Result so far: 6823.23
Subtracting 63 from 80 leaves us with 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Moving on to step 9:
170 divided by 21 is 8 with a remainder of 2.
Use 8 as the next digit of our solution. 
Result so far: 6823.238
Subtracting 168 from 170 leaves us with 2.
Since there are no more digits in the dividend, we add a zero to the remainder making it 20, and continue the process.

Moving on to step 10:
When dividing 20 by 21, we get 0 with a remainder of 20.
Record the quotient 0 as the next digit in the result. 
Result so far: 6823.238
The remainder is 20 after subtracting 0 from 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Let's proceed to step 11:
21 can be fit into 200 9 times, resulting in a remainder of 11.
Use 9 as the next digit of our solution. 
Result so far: 6823.23809
The remainder is 11 after subtracting 189 from 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Let's proceed to step 12:
110 divided by 21 is 5 with a remainder of 5.
The next digit of our result is 5. 
Result so far: 6823.238095
Deduct 105 from 110 and we're left with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Step 13:
The number 21 fits into 50 2 times, leaving a remainder of 8.
The next digit of our result is 2. 
Result so far: 6823.2380952
If we take 42 away from 50, we end up with 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Going ahead to step 14:
If we divide 80 by 21, we get 3 and a remainder of 17.
The next digit of our result is 3. 
Result so far: 6823.23809523
If we subtract 63 from 80, we get 17.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

The quotient of the division is 6823.23809523, and the remainder is 1.7e-08.