12997236 ÷ 646 
We want to figure out the number of times 12997236 can be divided by 646.

On to step 1:
If we divide 1 by 646, we get 0 and a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
Deduct 0 from 1 and we're left with 1.
Fetch the next digit (2) from the dividend, attach it to 1 and continue: 12 / 646

Going ahead to step 2:
The number 646 fits into 12 0 times, leaving a remainder of 12.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtract 0 from 12 to get 12.
Bring next digit (9) of the dividend behind the 12 and repeat the process: 129 / 646

On to step 3:
When dividing 129 by 646, we get 0 with a remainder of 129.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Deduct 0 from 129 and we're left with 129.
Grab the next digit (9) from the dividend, add it to 129, then carry on: 1299 / 646

Step 4:
If we divide 1299 by 646, we get 2 and a remainder of 7.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Subtracting 1292 from 1299 leaves us with 7.
Take the next digit (7) from the dividend and append it to 7, then repeat: 77 / 646

Going ahead to step 5:
646 goes into 77 0 times with a remainder of 77.
Record the quotient 0 as the next digit in the result. 
Result so far: 20.0
Subtract 0 from 77 to get 77.
Fetch the next digit (2) from the dividend, attach it to 77 and continue: 772 / 646

Let's proceed to step 6:
When dividing 772 by 646, we get 1 with a remainder of 126.
The next digit of our result is 1. 
Result so far: 201.0
Deduct 646 from 772 and we're left with 126.
Bring next digit (3) of the dividend behind the 126 and repeat the process: 1263 / 646

On to step 7:
646 goes into 1263 1 times with a remainder of 617.
The number 1 becomes the next digit in our result. 
Result so far: 2011.0
Deduct 646 from 1263 and we're left with 617.
Fetch the next digit (6) from the dividend, attach it to 617 and continue: 6176 / 646

Moving on to step 8:
646 goes into 6176 9 times with a remainder of 362.
Put 9 as the next digit of the answer. 
Result so far: 20119.0
The remainder is 362 after subtracting 5814 from 6176.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3620, and continue the process.

Going ahead to step 9:
The number 646 fits into 3620 5 times, leaving a remainder of 390.
Put 5 as the next digit of the answer. 
Result so far: 20119.5
The remainder is 390 after subtracting 3230 from 3620.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3900, and continue the process.

Advancing to step 10:
646 goes into 3900 6 times with a remainder of 24.
Use 6 as the next digit of our solution. 
Result so far: 20119.56
If we subtract 3876 from 3900, we get 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Step 11:
240 divided by 646 is 0 with a remainder of 240.
The next digit of our result is 0. 
Result so far: 20119.56
If we subtract 0 from 240, we get 240.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2400, and continue the process.

Moving on to step 12:
When dividing 2400 by 646, we get 3 with a remainder of 462.
The next digit of our result is 3. 
Result so far: 20119.5603
If we subtract 1938 from 2400, we get 462.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4620, and continue the process.

On to step 13:
If we divide 4620 by 646, we get 7 and a remainder of 98.
Record the quotient 7 as the next digit in the result. 
Result so far: 20119.56037
Subtract 4522 from 4620 to get 98.
Since there are no more digits in the dividend, we add a zero to the remainder making it 980, and continue the process.

On to step 14:
If we divide 980 by 646, we get 1 and a remainder of 334.
The next digit of our result is 1. 
Result so far: 20119.560371
The remainder is 334 after subtracting 646 from 980.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3340, and continue the process.

Let's proceed to step 15:
The number 646 fits into 3340 5 times, leaving a remainder of 110.
Record the quotient 5 as the next digit in the result. 
Result so far: 20119.5603715
The remainder is 110 after subtracting 3230 from 3340.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1100, and continue the process.

Let's proceed to step 16:
If we divide 1100 by 646, we get 1 and a remainder of 454.
Put 1 as the next digit of the answer. 
Result so far: 20119.56037151
If we take 646 away from 1100, we end up with 454.
Since there are no more digits in the dividend, we add a zero to the remainder making it 4540, and continue the process.

Our division results in 20119.56037151 with a remaining 4.54e-07.