We look at the division of 787543 by 21 
We want to figure out the number of times 787543 can be divided by 21.

On to step 1:
The number 21 fits into 7 0 times, leaving a remainder of 7.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 7, we end up with 7.
Fetch the next digit (8) from the dividend, attach it to 7 and continue: 78 / 21

Step 2:
The number 21 fits into 78 3 times, leaving a remainder of 15.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
Subtract 63 from 78 to get 15.
Append the next digit (7) from the dividend to 15 and continue with: 157 / 21

Advancing to step 3:
21 can be fit into 157 7 times, resulting in a remainder of 10.
The number 7 becomes the next digit in our result. 
Result so far: 37.0
The remainder is 10 after subtracting 147 from 157.
Append the next digit (5) from the dividend to 10 and continue with: 105 / 21

Let's proceed to step 4:
The number 21 fits into 105 5 times, leaving a remainder of 0.
Put 5 as the next digit of the answer. 
Result so far: 375.0
Subtract 105 from 105 to get 0.
Take the next digit (4) from the dividend and append it to 0, then repeat: 4 / 21

Moving on to step 5:
21 goes into 4 0 times with a remainder of 4.
Write down 0 as next digit of the result. 
Result so far: 3750.0
The remainder is 4 after subtracting 0 from 4.
Fetch the next digit (3) from the dividend, attach it to 4 and continue: 43 / 21

Let's proceed to step 6:
The number 21 fits into 43 2 times, leaving a remainder of 1.
The number 2 becomes the next digit in our result. 
Result so far: 37502.0
The remainder is 1 after subtracting 42 from 43.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Moving on to step 7:
10 divided by 21 is 0 with a remainder of 10.
Record the quotient 0 as the next digit in the result. 
Result so far: 37502.0
If we take 0 away from 10, we end up with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Going ahead to step 8:
21 goes into 100 4 times with a remainder of 16.
Put 4 as the next digit of the answer. 
Result so far: 37502.04
If we subtract 84 from 100, we get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Moving on to step 9:
The number 21 fits into 160 7 times, leaving a remainder of 13.
The number 7 becomes the next digit in our result. 
Result so far: 37502.047
Subtract 147 from 160 to get 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

On to step 10:
The number 21 fits into 130 6 times, leaving a remainder of 4.
Write down 6 as next digit of the result. 
Result so far: 37502.0476
Subtract 126 from 130 to get 4.
Since there are no more digits in the dividend, we add a zero to the remainder making it 40, and continue the process.

Advancing to step 11:
40 divided by 21 is 1 with a remainder of 19.
The next digit of our result is 1. 
Result so far: 37502.04761
Subtract 21 from 40 to get 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Step 12:
21 goes into 190 9 times with a remainder of 1.
Use 9 as the next digit of our solution. 
Result so far: 37502.047619
If we take 189 away from 190, we end up with 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Advancing to step 13:
21 can be fit into 10 0 times, resulting in a remainder of 10.
The number 0 becomes the next digit in our result. 
Result so far: 37502.047619
Deduct 0 from 10 and we're left with 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Step 14:
The number 21 fits into 100 4 times, leaving a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 37502.04761904
If we subtract 84 from 100, we get 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

The quotient of the division is 37502.04761904, and the remainder is 1.6e-08.