643512 ÷ 1 
Our goal is to divide 643512 by 1.

Going ahead to step 1:
1 can be fit into 6 6 times, resulting in a remainder of 0.
Record the quotient 6 as the next digit in the result. 
Result so far: 6.0
If we take 6 away from 6, we end up with 0.
Take the next digit (4) from the dividend and append it to 0, then repeat: 4 / 1

Advancing to step 2:
The number 1 fits into 4 4 times, leaving a remainder of 0.
Write down 4 as next digit of the result. 
Result so far: 64.0
Deduct 4 from 4 and we're left with 0.
Fetch the next digit (3) from the dividend, attach it to 0 and continue: 3 / 1

Advancing to step 3:
1 can be fit into 3 3 times, resulting in a remainder of 0.
Record the quotient 3 as the next digit in the result. 
Result so far: 643.0
If we subtract 3 from 3, we get 0.
Include the next digit (5) from the dividend after 0, then repeat: 5 / 1

Going ahead to step 4:
1 can be fit into 5 5 times, resulting in a remainder of 0.
Write down 5 as next digit of the result. 
Result so far: 6435.0
If we take 5 away from 5, we end up with 0.
Append the next digit (1) from the dividend to 0 and continue with: 1 / 1

On to step 5:
When dividing 1 by 1, we get 1 with a remainder of 0.
Use 1 as the next digit of our solution. 
Result so far: 64351.0
If we take 1 away from 1, we end up with 0.
Bring next digit (2) of the dividend behind the 0 and repeat the process: 2 / 1

Step 6:
1 goes into 2 2 times with a remainder of 0.
Record the quotient 2 as the next digit in the result. 
Result so far: 643512.0
Deduct 2 from 2 and we're left with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Step 7:
If we divide 0 by 1, we get 0 and a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 643512.0
If we subtract 0 from 0, we get 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

On to step 8:
1 goes into 0 0 times with a remainder of 0.
The next digit of our result is 0. 
Result so far: 643512.0
The remainder is 0 after subtracting 0 from 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

The final result is 643512.0 with a remainder of 0.0.