19937539 ÷ 644 
We want to divide 19937539 by 644.

Let's proceed to step 1:
644 goes into 1 0 times with a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 1, we get 1.
Grab the next digit (9) from the dividend, add it to 1, then carry on: 19 / 644

On to step 2:
19 divided by 644 is 0 with a remainder of 19.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 19, we get 19.
Take the next digit (9) from the dividend and append it to 19, then repeat: 199 / 644

Moving on to step 3:
199 divided by 644 is 0 with a remainder of 199.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
Deduct 0 from 199 and we're left with 199.
Take the next digit (3) from the dividend and append it to 199, then repeat: 1993 / 644

Moving on to step 4:
When dividing 1993 by 644, we get 3 with a remainder of 61.
The next digit of our result is 3. 
Result so far: 3.0
Deduct 1932 from 1993 and we're left with 61.
Append the next digit (7) from the dividend to 61 and continue with: 617 / 644

Moving on to step 5:
644 goes into 617 0 times with a remainder of 617.
Write down 0 as next digit of the result. 
Result so far: 30.0
Deduct 0 from 617 and we're left with 617.
Take the next digit (5) from the dividend and append it to 617, then repeat: 6175 / 644

Step 6:
When dividing 6175 by 644, we get 9 with a remainder of 379.
The next digit of our result is 9. 
Result so far: 309.0
If we subtract 5796 from 6175, we get 379.
Grab the next digit (3) from the dividend, add it to 379, then carry on: 3793 / 644

Moving on to step 7:
If we divide 3793 by 644, we get 5 and a remainder of 573.
Use 5 as the next digit of our solution. 
Result so far: 3095.0
Subtracting 3220 from 3793 leaves us with 573.
Take the next digit (9) from the dividend and append it to 573, then repeat: 5739 / 644

Moving on to step 8:
When dividing 5739 by 644, we get 8 with a remainder of 587.
The number 8 becomes the next digit in our result. 
Result so far: 30958.0
Subtract 5152 from 5739 to get 587.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5870, and continue the process.

On to step 9:
644 can be fit into 5870 9 times, resulting in a remainder of 74.
The next digit of our result is 9. 
Result so far: 30958.9
Deduct 5796 from 5870 and we're left with 74.
Since there are no more digits in the dividend, we add a zero to the remainder making it 740, and continue the process.

Step 10:
When dividing 740 by 644, we get 1 with a remainder of 96.
Use 1 as the next digit of our solution. 
Result so far: 30958.91
Subtract 644 from 740 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 11:
If we divide 960 by 644, we get 1 and a remainder of 316.
Record the quotient 1 as the next digit in the result. 
Result so far: 30958.911
Subtract 644 from 960 to get 316.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3160, and continue the process.

Our division results in 30958.911 with a remaining 0.0316.