99905644 divided by 646 
Let's see how many times 646 fits into 99905644.

Advancing to step 1:
646 can be fit into 9 0 times, resulting in a remainder of 9.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
If we subtract 0 from 9, we get 9.
Bring next digit (9) of the dividend behind the 9 and repeat the process: 99 / 646

Step 2:
646 can be fit into 99 0 times, resulting in a remainder of 99.
Write down 0 as next digit of the result. 
Result so far: 0.0
The remainder is 99 after subtracting 0 from 99.
Append the next digit (9) from the dividend to 99 and continue with: 999 / 646

Let's proceed to step 3:
999 divided by 646 is 1 with a remainder of 353.
Put 1 as the next digit of the answer. 
Result so far: 1.0
If we take 646 away from 999, we end up with 353.
Grab the next digit (0) from the dividend, add it to 353, then carry on: 3530 / 646

Moving on to step 4:
When dividing 3530 by 646, we get 5 with a remainder of 300.
The number 5 becomes the next digit in our result. 
Result so far: 15.0
If we subtract 3230 from 3530, we get 300.
Grab the next digit (5) from the dividend, add it to 300, then carry on: 3005 / 646

On to step 5:
646 goes into 3005 4 times with a remainder of 421.
The next digit of our result is 4. 
Result so far: 154.0
Deduct 2584 from 3005 and we're left with 421.
Bring next digit (6) of the dividend behind the 421 and repeat the process: 4216 / 646

Moving on to step 6:
If we divide 4216 by 646, we get 6 and a remainder of 340.
Write down 6 as next digit of the result. 
Result so far: 1546.0
Subtract 3876 from 4216 to get 340.
Include the next digit (4) from the dividend after 340, then repeat: 3404 / 646

On to step 7:
646 goes into 3404 5 times with a remainder of 174.
Write down 5 as next digit of the result. 
Result so far: 15465.0
Deduct 3230 from 3404 and we're left with 174.
Append the next digit (4) from the dividend to 174 and continue with: 1744 / 646

Going ahead to step 8:
The number 646 fits into 1744 2 times, leaving a remainder of 452.
Record the quotient 2 as the next digit in the result. 
Result so far: 154652.0
Deduct 1292 from 1744 and we're left with 452.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4520, and continue the process.

Going ahead to step 9:
If we divide 4520 by 646, we get 6 and a remainder of 644.
Put 6 as the next digit of the answer. 
Result so far: 154652.6
If we take 3876 away from 4520, we end up with 644.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6440, and continue the process.

Moving on to step 10:
If we divide 6440 by 646, we get 9 and a remainder of 626.
Record the quotient 9 as the next digit in the result. 
Result so far: 154652.69
Deduct 5814 from 6440 and we're left with 626.
Since there are no more digits in the dividend, we add a zero to the remainder making it 6260, and continue the process.

Let's proceed to step 11:
When dividing 6260 by 646, we get 9 with a remainder of 446.
Write down 9 as next digit of the result. 
Result so far: 154652.699
Subtracting 5814 from 6260 leaves us with 446.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4460, and continue the process.

The final result is 154652.699 with a remainder of 0.0446.