58551221 ÷ 644 
We want to figure out the number of times 58551221 can be divided by 644.

Step 1:
644 can be fit into 5 0 times, resulting in a remainder of 5.
Use 0 as the next digit of our solution. 
Result so far: 0.0
If we take 0 away from 5, we end up with 5.
Append the next digit (8) from the dividend to 5 and continue with: 58 / 644

Step 2:
644 can be fit into 58 0 times, resulting in a remainder of 58.
Use 0 as the next digit of our solution. 
Result so far: 0.0
The remainder is 58 after subtracting 0 from 58.
Grab the next digit (5) from the dividend, add it to 58, then carry on: 585 / 644

Advancing to step 3:
If we divide 585 by 644, we get 0 and a remainder of 585.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtracting 0 from 585 leaves us with 585.
Grab the next digit (5) from the dividend, add it to 585, then carry on: 5855 / 644

Moving on to step 4:
644 can be fit into 5855 9 times, resulting in a remainder of 59.
The next digit of our result is 9. 
Result so far: 9.0
If we subtract 5796 from 5855, we get 59.
Bring next digit (1) of the dividend behind the 59 and repeat the process: 591 / 644

Going ahead to step 5:
If we divide 591 by 644, we get 0 and a remainder of 591.
Use 0 as the next digit of our solution. 
Result so far: 90.0
Subtracting 0 from 591 leaves us with 591.
Include the next digit (2) from the dividend after 591, then repeat: 5912 / 644

Advancing to step 6:
644 can be fit into 5912 9 times, resulting in a remainder of 116.
Use 9 as the next digit of our solution. 
Result so far: 909.0
Deduct 5796 from 5912 and we're left with 116.
Append the next digit (2) from the dividend to 116 and continue with: 1162 / 644

On to step 7:
1162 divided by 644 is 1 with a remainder of 518.
Put 1 as the next digit of the answer. 
Result so far: 9091.0
If we subtract 644 from 1162, we get 518.
Bring next digit (1) of the dividend behind the 518 and repeat the process: 5181 / 644

Advancing to step 8:
5181 divided by 644 is 8 with a remainder of 29.
The next digit of our result is 8. 
Result so far: 90918.0
Subtracting 5152 from 5181 leaves us with 29.
Since there are no more digits in the dividend, we add a zero to the remainder making it 290, and continue the process.

Let's proceed to step 9:
If we divide 290 by 644, we get 0 and a remainder of 290.
The number 0 becomes the next digit in our result. 
Result so far: 90918.0
The remainder is 290 after subtracting 0 from 290.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2900, and continue the process.

On to step 10:
2900 divided by 644 is 4 with a remainder of 324.
The next digit of our result is 4. 
Result so far: 90918.04
Subtract 2576 from 2900 to get 324.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3240, and continue the process.

Advancing to step 11:
644 can be fit into 3240 5 times, resulting in a remainder of 20.
Record the quotient 5 as the next digit in the result. 
Result so far: 90918.045
Subtract 3220 from 3240 to get 20.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Advancing to step 12:
If we divide 200 by 644, we get 0 and a remainder of 200.
Write down 0 as next digit of the result. 
Result so far: 90918.045
Subtract 0 from 200 to get 200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2000, and continue the process.

On to step 13:
644 can be fit into 2000 3 times, resulting in a remainder of 68.
The next digit of our result is 3. 
Result so far: 90918.04503
Subtracting 1932 from 2000 leaves us with 68.
Since there are no more digits in the dividend, we add a zero to the remainder making it 680, and continue the process.

Advancing to step 14:
644 can be fit into 680 1 times, resulting in a remainder of 36.
The number 1 becomes the next digit in our result. 
Result so far: 90918.045031
The remainder is 36 after subtracting 644 from 680.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

On to step 15:
644 goes into 360 0 times with a remainder of 360.
The number 0 becomes the next digit in our result. 
Result so far: 90918.045031
Subtracting 0 from 360 leaves us with 360.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3600, and continue the process.

Moving on to step 16:
644 can be fit into 3600 5 times, resulting in a remainder of 380.
The next digit of our result is 5. 
Result so far: 90918.04503105
If we take 3220 away from 3600, we end up with 380.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3800, and continue the process.

Our division results in 90918.04503105 with a remaining 3.8e-07.