358541 ÷ 21 
We want to figure out the number of times 358541 can be divided by 21.

Step 1:
The number 21 fits into 3 0 times, leaving a remainder of 3.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 3 leaves us with 3.
Grab the next digit (5) from the dividend, add it to 3, then carry on: 35 / 21

On to step 2:
If we divide 35 by 21, we get 1 and a remainder of 14.
The next digit of our result is 1. 
Result so far: 1.0
The remainder is 14 after subtracting 21 from 35.
Append the next digit (8) from the dividend to 14 and continue with: 148 / 21

On to step 3:
If we divide 148 by 21, we get 7 and a remainder of 1.
The next digit of our result is 7. 
Result so far: 17.0
The remainder is 1 after subtracting 147 from 148.
Take the next digit (5) from the dividend and append it to 1, then repeat: 15 / 21

Going ahead to step 4:
15 divided by 21 is 0 with a remainder of 15.
The next digit of our result is 0. 
Result so far: 170.0
Subtracting 0 from 15 leaves us with 15.
Append the next digit (4) from the dividend to 15 and continue with: 154 / 21

On to step 5:
21 can be fit into 154 7 times, resulting in a remainder of 7.
Put 7 as the next digit of the answer. 
Result so far: 1707.0
The remainder is 7 after subtracting 147 from 154.
Append the next digit (1) from the dividend to 7 and continue with: 71 / 21

Going ahead to step 6:
If we divide 71 by 21, we get 3 and a remainder of 8.
Put 3 as the next digit of the answer. 
Result so far: 17073.0
The remainder is 8 after subtracting 63 from 71.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

Let's proceed to step 7:
The number 21 fits into 80 3 times, leaving a remainder of 17.
Record the quotient 3 as the next digit in the result. 
Result so far: 17073.3
The remainder is 17 after subtracting 63 from 80.
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 8:
170 divided by 21 is 8 with a remainder of 2.
Put 8 as the next digit of the answer. 
Result so far: 17073.38
If we subtract 168 from 170, we get 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 9:
When dividing 20 by 21, we get 0 with a remainder of 20.
Write down 0 as next digit of the result. 
Result so far: 17073.38
Subtract 0 from 20 to get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

On to step 10:
The number 21 fits into 200 9 times, leaving a remainder of 11.
Record the quotient 9 as the next digit in the result. 
Result so far: 17073.3809
Subtract 189 from 200 to get 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Step 11:
The number 21 fits into 110 5 times, leaving a remainder of 5.
The number 5 becomes the next digit in our result. 
Result so far: 17073.38095
The remainder is 5 after subtracting 105 from 110.
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 12:
21 can be fit into 50 2 times, resulting in a remainder of 8.
The next digit of our result is 2. 
Result so far: 17073.380952
If we subtract 42 from 50, we get 8.
Since there are no more digits in the dividend, we add a zero to the remainder making it 80, and continue the process.

On to step 13:
21 can be fit into 80 3 times, resulting in a remainder of 17.
The number 3 becomes the next digit in our result. 
Result so far: 17073.3809523
The remainder is 17 after subtracting 63 from 80.
Since there are no more digits in the dividend, we add a zero to the remainder making it 170, and continue the process.

Going ahead to step 14:
21 goes into 170 8 times with a remainder of 2.
The number 8 becomes the next digit in our result. 
Result so far: 17073.38095238
If we take 168 away from 170, we end up 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.

The final outcome is 17073.38095238, with a leftover of 2e-09.