21534514 ÷ 643 
We want to figure out the number of times 21534514 can be divided by 643.

Step 1:
2 divided by 643 is 0 with a remainder of 2.
Write down 0 as next digit of the result. 
Result so far: 0.0
If we subtract 0 from 2, we get 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 643

Let's proceed to step 2:
When dividing 21 by 643, we get 0 with a remainder of 21.
Put 0 as the next digit of the answer. 
Result so far: 0.0
If we subtract 0 from 21, we get 21.
Append the next digit (5) from the dividend to 21 and continue with: 215 / 643

Step 3:
When dividing 215 by 643, we get 0 with a remainder of 215.
Put 0 as the next digit of the answer. 
Result so far: 0.0
The remainder is 215 after subtracting 0 from 215.
Take the next digit (3) from the dividend and append it to 215, then repeat: 2153 / 643

Moving on to step 4:
643 goes into 2153 3 times with a remainder of 224.
Record the quotient 3 as the next digit in the result. 
Result so far: 3.0
Deduct 1929 from 2153 and we're left with 224.
Append the next digit (4) from the dividend to 224 and continue with: 2244 / 643

Going ahead to step 5:
643 can be fit into 2244 3 times, resulting in a remainder of 315.
Record the quotient 3 as the next digit in the result. 
Result so far: 33.0
If we subtract 1929 from 2244, we get 315.
Fetch the next digit (5) from the dividend, attach it to 315 and continue: 3155 / 643

Going ahead to step 6:
When dividing 3155 by 643, we get 4 with a remainder of 583.
Record the quotient 4 as the next digit in the result. 
Result so far: 334.0
Subtracting 2572 from 3155 leaves us with 583.
Include the next digit (1) from the dividend after 583, then repeat: 5831 / 643

Step 7:
643 can be fit into 5831 9 times, resulting in a remainder of 44.
The number 9 becomes the next digit in our result. 
Result so far: 3349.0
Deduct 5787 from 5831 and we're left with 44.
Fetch the next digit (4) from the dividend, attach it to 44 and continue: 444 / 643

On to step 8:
If we divide 444 by 643, we get 0 and a remainder of 444.
The next digit of our result is 0. 
Result so far: 33490.0
Subtracting 0 from 444 leaves us with 444.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4440, and continue the process.

Let's proceed to step 9:
If we divide 4440 by 643, we get 6 and a remainder of 582.
The next digit of our result is 6. 
Result so far: 33490.6
The remainder is 582 after subtracting 3858 from 4440.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5820, and continue the process.

On to step 10:
643 can be fit into 5820 9 times, resulting in a remainder of 33.
The next digit of our result is 9. 
Result so far: 33490.69
If we take 5787 away from 5820, we end up with 33.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

Let's proceed to step 11:
The number 643 fits into 330 0 times, leaving a remainder of 330.
Use 0 as the next digit of our solution. 
Result so far: 33490.69
Deduct 0 from 330 and we're left with 330.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3300, and continue the process.

Moving on to step 12:
When dividing 3300 by 643, we get 5 with a remainder of 85.
The next digit of our result is 5. 
Result so far: 33490.6905
Deduct 3215 from 3300 and we're left with 85.
Since there are no more digits in the dividend, we add a zero to the remainder making it 850, and continue the process.

On to step 13:
850 divided by 643 is 1 with a remainder of 207.
The next digit of our result is 1. 
Result so far: 33490.69051
If we subtract 643 from 850, we get 207.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2070, and continue the process.

Moving on to step 14:
643 goes into 2070 3 times with a remainder of 141.
The next digit of our result is 3. 
Result so far: 33490.690513
If we subtract 1929 from 2070, we get 141.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1410, and continue the process.

Moving on to step 15:
1410 divided by 643 is 2 with a remainder of 124.
Put 2 as the next digit of the answer. 
Result so far: 33490.6905132
Subtracting 1286 from 1410 leaves us with 124.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1240, and continue the process.

Going ahead to step 16:
When dividing 1240 by 643, we get 1 with a remainder of 597.
Record the quotient 1 as the next digit in the result. 
Result so far: 33490.69051321
Deduct 643 from 1240 and we're left with 597.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5970, and continue the process.

The final outcome is 33490.69051321, with a leftover of 5.97e-07.