640671 ÷ 51 
We're looking to find how many times 51 goes into 640671.

Let's proceed to step 1:
When dividing 6 by 51, we get 0 with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
If we subtract 0 from 6, we get 6.
Fetch the next digit (4) from the dividend, attach it to 6 and continue: 64 / 51

Going ahead to step 2:
If we divide 64 by 51, we get 1 and a remainder of 13.
The next digit of our result is 1. 
Result so far: 1.0
Subtract 51 from 64 to get 13.
Take the next digit (0) from the dividend and append it to 13, then repeat: 130 / 51

On to step 3:
130 divided by 51 is 2 with a remainder of 28.
Put 2 as the next digit of the answer. 
Result so far: 12.0
If we take 102 away from 130, we end up with 28.
Grab the next digit (6) from the dividend, add it to 28, then carry on: 286 / 51

Step 4:
51 goes into 286 5 times with a remainder of 31.
Use 5 as the next digit of our solution. 
Result so far: 125.0
If we take 255 away from 286, we end up with 31.
Grab the next digit (7) from the dividend, add it to 31, then carry on: 317 / 51

Step 5:
51 can be fit into 317 6 times, resulting in a remainder of 11.
Write down 6 as next digit of the result. 
Result so far: 1256.0
The remainder is 11 after subtracting 306 from 317.
Grab the next digit (1) from the dividend, add it to 11, then carry on: 111 / 51

Step 6:
When dividing 111 by 51, we get 2 with a remainder of 9.
Use 2 as the next digit of our solution. 
Result so far: 12562.0
If we take 102 away from 111, we end up with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Let's proceed to step 7:
If we divide 90 by 51, we get 1 and a remainder of 39.
Use 1 as the next digit of our solution. 
Result so far: 12562.1
The remainder is 39 after subtracting 51 from 90.
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 8:
51 goes into 390 7 times with a remainder of 33.
Record the quotient 7 as the next digit in the result. 
Result so far: 12562.17
Subtract 357 from 390 to get 33.
Since there are no more digits in the dividend, we add a zero to the remainder making it 330, and continue the process.

Advancing to step 9:
When dividing 330 by 51, we get 6 with a remainder of 24.
Record the quotient 6 as the next digit in the result. 
Result so far: 12562.176
Deduct 306 from 330 and we're left with 24.
Since there are no more digits in the dividend, we add a zero to the remainder making it 240, and continue the process.

Going ahead to step 10:
The number 51 fits into 240 4 times, leaving a remainder of 36.
Record the quotient 4 as the next digit in the result. 
Result so far: 12562.1764
Subtracting 204 from 240 leaves us with 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Step 11:
51 can be fit into 360 7 times, resulting in a remainder of 3.
Put 7 as the next digit of the answer. 
Result so far: 12562.17647
Deduct 357 from 360 and we're left with 3.
Since there are no more digits in the dividend, we add a zero to the remainder making it 30, and continue the process.

Step 12:
51 goes into 30 0 times with a remainder of 30.
The next digit of our result is 0. 
Result so far: 12562.17647
If we take 0 away from 30, we end up with 30.
Since there are no more digits in the dividend, we add a zero to the remainder making it 300, and continue the process.

On to step 13:
If we divide 300 by 51, we get 5 and a remainder of 45.
Put 5 as the next digit of the answer. 
Result so far: 12562.1764705
If we take 255 away from 300, we end up with 45.
Since there are no more digits in the dividend, we add a zero to the remainder making it 450, and continue the process.

Let's proceed to step 14:
51 goes into 450 8 times with a remainder of 42.
Write down 8 as next digit of the result. 
Result so far: 12562.17647058
If we take 408 away from 450, we end up with 42.
Since there are no more digits in the dividend, we add a zero to the remainder making it 420, and continue the process.

After the division, we end up with 12562.17647058 and a remainder of 4.2e-08.