337253 ÷ 21 
Our goal is to divide 337253 by 21.

Advancing to step 1:
21 goes into 3 0 times with a remainder of 3.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 3, we end up with 3.
Append the next digit (3) from the dividend to 3 and continue with: 33 / 21

On to step 2:
The number 21 fits into 33 1 times, leaving a remainder of 12.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we take 21 away from 33, we end up with 12.
Fetch the next digit (7) from the dividend, attach it to 12 and continue: 127 / 21

Going ahead to step 3:
When dividing 127 by 21, we get 6 with a remainder of 1.
Use 6 as the next digit of our solution. 
Result so far: 16.0
If we subtract 126 from 127, we get 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 21

Going ahead to step 4:
21 can be fit into 12 0 times, resulting in a remainder of 12.
Put 0 as the next digit of the answer. 
Result so far: 160.0
If we take 0 away from 12, we end up with 12.
Include the next digit (5) from the dividend after 12, then repeat: 125 / 21

Step 5:
21 can be fit into 125 5 times, resulting in a remainder of 20.
Put 5 as the next digit of the answer. 
Result so far: 1605.0
The remainder is 20 after subtracting 105 from 125.
Grab the next digit (3) from the dividend, add it to 20, then carry on: 203 / 21

On to step 6:
203 divided by 21 is 9 with a remainder of 14.
Write down 9 as next digit of the result. 
Result so far: 16059.0
Deduct 189 from 203 and we're left with 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

Advancing to step 7:
21 goes into 140 6 times with a remainder of 14.
Write down 6 as next digit of the result. 
Result so far: 16059.6
If we subtract 126 from 140, we get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

On to step 8:
If we divide 140 by 21, we get 6 and a remainder of 14.
Write down 6 as next digit of the result. 
Result so far: 16059.66
If we subtract 126 from 140, we get 14.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

The final outcome is 16059.66, with a leftover of 0.014.