21285609 ÷ 307 
We want to figure out the number of times 21285609 can be divided by 307.

Let's proceed to step 1:
307 goes into 2 0 times with a remainder of 2.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 2 leaves us with 2.
Include the next digit (1) from the dividend after 2, then repeat: 21 / 307

Going ahead to step 2:
307 goes into 21 0 times 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.
Include the next digit (2) from the dividend after 21, then repeat: 212 / 307

Moving on to step 3:
212 divided by 307 is 0 with a remainder of 212.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 212 and we're left with 212.
Append the next digit (8) from the dividend to 212 and continue with: 2128 / 307

Going ahead to step 4:
When dividing 2128 by 307, we get 6 with a remainder of 286.
The number 6 becomes the next digit in our result. 
Result so far: 6.0
If we take 1842 away from 2128, we end up with 286.
Include the next digit (5) from the dividend after 286, then repeat: 2865 / 307

Advancing to step 5:
307 can be fit into 2865 9 times, resulting in a remainder of 102.
The number 9 becomes the next digit in our result. 
Result so far: 69.0
Subtracting 2763 from 2865 leaves us with 102.
Include the next digit (6) from the dividend after 102, then repeat: 1026 / 307

Advancing to step 6:
307 can be fit into 1026 3 times, resulting in a remainder of 105.
Write down 3 as next digit of the result. 
Result so far: 693.0
Deduct 921 from 1026 and we're left with 105.
Include the next digit (0) from the dividend after 105, then repeat: 1050 / 307

Moving on to step 7:
307 goes into 1050 3 times with a remainder of 129.
Use 3 as the next digit of our solution. 
Result so far: 6933.0
If we take 921 away from 1050, we end up with 129.
Take the next digit (9) from the dividend and append it to 129, then repeat: 1299 / 307

Moving on to step 8:
307 can be fit into 1299 4 times, resulting in a remainder of 71.
Record the quotient 4 as the next digit in the result. 
Result so far: 69334.0
Subtracting 1228 from 1299 leaves us with 71.
Since there are no more digits in the dividend, we add a zero to the remainder making it 710, and continue the process.

Let's proceed to step 9:
307 can be fit into 710 2 times, resulting in a remainder of 96.
Record the quotient 2 as the next digit in the result. 
Result so far: 69334.2
Subtract 614 from 710 to get 96.
Since there are no more digits in the dividend, we add a zero to the remainder making it 960, and continue the process.

On to step 10:
960 divided by 307 is 3 with a remainder of 39.
Write down 3 as next digit of the result. 
Result so far: 69334.23
The remainder is 39 after subtracting 921 from 960.
Since there are no more digits in the dividend, we add a zero to the remainder making it 390, and continue the process.

Advancing to step 11:
390 divided by 307 is 1 with a remainder of 83.
The next digit of our result is 1. 
Result so far: 69334.231
Deduct 307 from 390 and we're left with 83.
Since there are no more digits in the dividend, we add a zero to the remainder making it 830, and continue the process.

Advancing to step 12:
If we divide 830 by 307, we get 2 and a remainder of 216.
Use 2 as the next digit of our solution. 
Result so far: 69334.2312
Deduct 614 from 830 and we're left with 216.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2160, and continue the process.

Going ahead to step 13:
When dividing 2160 by 307, we get 7 with a remainder of 11.
Record the quotient 7 as the next digit in the result. 
Result so far: 69334.23127
If we take 2149 away from 2160, we end up with 11.
Since there are no more digits in the dividend, we add a zero to the remainder making it 110, and continue the process.

Going ahead to step 14:
When dividing 110 by 307, we get 0 with a remainder of 110.
The number 0 becomes the next digit in our result. 
Result so far: 69334.23127
Deduct 0 from 110 and we're left with 110.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1100, and continue the process.

Going ahead to step 15:
1100 divided by 307 is 3 with a remainder of 179.
Write down 3 as next digit of the result. 
Result so far: 69334.2312703
If we take 921 away from 1100, we end up with 179.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1790, and continue the process.

Going ahead to step 16:
307 goes into 1790 5 times with a remainder of 255.
Put 5 as the next digit of the answer. 
Result so far: 69334.23127035
Deduct 1535 from 1790 and we're left with 255.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2550, and continue the process.

The final result is 69334.23127035 with a remainder of 2.55e-07.