We look at the division of 350490 by 21 
Our goal is to divide 350490 by 21.

On to step 1:
21 can be fit into 3 0 times, resulting in a remainder of 3.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we take 0 away from 3, we end up with 3.
Include the next digit (5) from the dividend after 3, then repeat: 35 / 21

Advancing to step 2:
When dividing 35 by 21, we get 1 with a remainder of 14.
Record the quotient 1 as the next digit in the result. 
Result so far: 1.0
Subtracting 21 from 35 leaves us with 14.
Append the next digit (0) from the dividend to 14 and continue with: 140 / 21

Going ahead to step 3:
140 divided by 21 is 6 with a remainder of 14.
Write down 6 as next digit of the result. 
Result so far: 16.0
If we subtract 126 from 140, we get 14.
Grab the next digit (4) from the dividend, add it to 14, then carry on: 144 / 21

On to step 4:
The number 21 fits into 144 6 times, leaving a remainder of 18.
Put 6 as the next digit of the answer. 
Result so far: 166.0
Subtract 126 from 144 to get 18.
Append the next digit (9) from the dividend to 18 and continue with: 189 / 21

On to step 5:
When dividing 189 by 21, we get 9 with a remainder of 0.
Write down 9 as next digit of the result. 
Result so far: 1669.0
Subtract 189 from 189 to get 0.
Take the next digit (0) from the dividend and append it to 0, then repeat: 0 / 21

Let's proceed to step 6:
21 can be fit into 0 0 times, resulting in a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 16690.0
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

On to step 7:
The number 21 fits into 0 0 times, leaving a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 16690.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 8:
0 divided by 21 is 0 with a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 16690.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final result is 16690.0 with a remainder of 0.0.