We look at the division of 350394 by 21 
We're looking to find how many times 21 goes into 350394.

Moving on to step 1:
21 can be fit into 3 0 times, resulting in a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 3 to get 3.
Include the next digit (5) from the dividend after 3, then repeat: 35 / 21

Step 2:
The number 21 fits into 35 1 times, leaving a remainder of 14.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
Deduct 21 from 35 and we're left with 14.
Include the next digit (0) from the dividend after 14, then repeat: 140 / 21

Let's proceed to step 3:
21 can be fit into 140 6 times, resulting in a remainder of 14.
Write down 6 as next digit of the result. 
Result so far: 16.0
Subtract 126 from 140 to get 14.
Include the next digit (3) from the dividend after 14, then repeat: 143 / 21

Let's proceed to step 4:
21 can be fit into 143 6 times, resulting in a remainder of 17.
The number 6 becomes the next digit in our result. 
Result so far: 166.0
Deduct 126 from 143 and we're left with 17.
Grab the next digit (9) from the dividend, add it to 17, then carry on: 179 / 21

Let's proceed to step 5:
When dividing 179 by 21, we get 8 with a remainder of 11.
Put 8 as the next digit of the answer. 
Result so far: 1668.0
Subtract 168 from 179 to get 11.
Grab the next digit (4) from the dividend, add it to 11, then carry on: 114 / 21

Advancing to step 6:
21 goes into 114 5 times with a remainder of 9.
Put 5 as the next digit of the answer. 
Result so far: 16685.0
If we take 105 away from 114, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Let's proceed to step 7:
The number 21 fits into 90 4 times, leaving a remainder of 6.
Record the quotient 4 as the next digit in the result. 
Result so far: 16685.4
If we take 84 away from 90, we end up with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Step 8:
60 divided by 21 is 2 with a remainder of 18.
Use 2 as the next digit of our solution. 
Result so far: 16685.42
If we take 42 away from 60, we end up with 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

Advancing to step 9:
When dividing 180 by 21, we get 8 with a remainder of 12.
Write down 8 as next digit of the result. 
Result so far: 16685.428
Subtract 168 from 180 to get 12.
Since there are no more digits in the dividend, we add a zero to the remainder making it 120, and continue the process.

Let's proceed to step 10:
If we divide 120 by 21, we get 5 and a remainder of 15.
The next digit of our result is 5. 
Result so far: 16685.4285
Subtract 105 from 120 to get 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

On to step 11:
If we divide 150 by 21, we get 7 and a remainder of 3.
The next digit of our result is 7. 
Result so far: 16685.42857
If we subtract 147 from 150, we get 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Let's proceed to step 12:
21 can be fit into 30 1 times, resulting in a remainder of 9.
The number 1 becomes the next digit in our result. 
Result so far: 16685.428571
The remainder is 9 after subtracting 21 from 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Moving on to step 13:
If we divide 90 by 21, we get 4 and a remainder of 6.
Put 4 as the next digit of the answer. 
Result so far: 16685.4285714
Deduct 84 from 90 and we're left with 6.
Since there are no more digits in the dividend, we add a zero to the remainder making it 60, and continue the process.

Let's proceed to step 14:
The number 21 fits into 60 2 times, leaving a remainder of 18.
The number 2 becomes the next digit in our result. 
Result so far: 16685.42857142
If we subtract 42 from 60, we get 18.
Since there are no more digits in the dividend, we add a zero to the remainder making it 180, and continue the process.

In conclusion, the division gives 16685.42857142 with a balance of 1.8e-08.