We're dividing 125434 by 21 
We're looking to find how many times 21 goes into 125434.

On to step 1:
The number 21 fits into 1 0 times, leaving a remainder of 1.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Take the next digit (2) from the dividend and append it to 1, then repeat: 12 / 21

On to step 2:
21 goes into 12 0 times with a remainder of 12.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 12 to get 12.
Grab the next digit (5) from the dividend, add it to 12, then carry on: 125 / 21

Step 3:
125 divided by 21 is 5 with a remainder of 20.
Record the quotient 5 as the next digit in the result. 
Result so far: 5.0
If we take 105 away from 125, we end up with 20.
Bring next digit (4) of the dividend behind the 20 and repeat the process: 204 / 21

Advancing to step 4:
When dividing 204 by 21, we get 9 with a remainder of 15.
Record the quotient 9 as the next digit in the result. 
Result so far: 59.0
Deduct 189 from 204 and we're left with 15.
Grab the next digit (3) from the dividend, add it to 15, then carry on: 153 / 21

On to step 5:
21 goes into 153 7 times with a remainder of 6.
Write down 7 as next digit of the result. 
Result so far: 597.0
Subtract 147 from 153 to get 6.
Fetch the next digit (4) from the dividend, attach it to 6 and continue: 64 / 21

Step 6:
21 can be fit into 64 3 times, resulting in a remainder of 1.
Write down 3 as next digit of the result. 
Result so far: 5973.0
If we subtract 63 from 64, we get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 7:
10 divided by 21 is 0 with a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 5973.0
If we subtract 0 from 10, we get 10.
Since there are no more digits in the dividend, we add a zero to the remainder making it 100, and continue the process.

Moving on to step 8:
21 goes into 100 4 times with a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 5973.04
The remainder is 16 after subtracting 84 from 100.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

Going ahead to step 9:
When dividing 160 by 21, we get 7 with a remainder of 13.
Use 7 as the next digit of our solution. 
Result so far: 5973.047
Deduct 147 from 160 and we're left with 13.
Since there are no more digits in the dividend, we add a zero to the remainder making it 130, and continue the process.

Going ahead to step 10:
130 divided by 21 is 6 with a remainder of 4.
The number 6 becomes the next digit in our result. 
Result so far: 5973.0476
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.

On to step 11:
21 goes into 40 1 times with a remainder of 19.
Write down 1 as next digit of the result. 
Result so far: 5973.04761
Deduct 21 from 40 and we're left with 19.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Going ahead to step 12:
When dividing 190 by 21, we get 9 with a remainder of 1.
Record the quotient 9 as the next digit in the result. 
Result so far: 5973.047619
Subtract 189 from 190 to get 1.
Since there are no more digits in the dividend, we add a zero to the remainder making it 10, and continue the process.

Step 13:
If we divide 10 by 21, we get 0 and a remainder of 10.
Put 0 as the next digit of the answer. 
Result so far: 5973.047619
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.

Advancing to step 14:
21 goes into 100 4 times with a remainder of 16.
The number 4 becomes the next digit in our result. 
Result so far: 5973.04761904
Deduct 84 from 100 and we're left with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

In conclusion, the division gives 5973.04761904 with a balance of 1.6e-08.