644163 divided by 86 
We're looking to find how many times 86 goes into 644163.

Let's proceed to step 1:
When dividing 6 by 86, we get 0 with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
The remainder is 6 after subtracting 0 from 6.
Bring next digit (4) of the dividend behind the 6 and repeat the process: 64 / 86

On to step 2:
If we divide 64 by 86, we get 0 and a remainder of 64.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Deduct 0 from 64 and we're left with 64.
Take the next digit (4) from the dividend and append it to 64, then repeat: 644 / 86

On to step 3:
86 can be fit into 644 7 times, resulting in a remainder of 42.
Write down 7 as next digit of the result. 
Result so far: 7.0
Deduct 602 from 644 and we're left with 42.
Grab the next digit (1) from the dividend, add it to 42, then carry on: 421 / 86

Moving on to step 4:
86 goes into 421 4 times with a remainder of 77.
Put 4 as the next digit of the answer. 
Result so far: 74.0
Deduct 344 from 421 and we're left with 77.
Take the next digit (6) from the dividend and append it to 77, then repeat: 776 / 86

Let's proceed to step 5:
776 divided by 86 is 9 with a remainder of 2.
Put 9 as the next digit of the answer. 
Result so far: 749.0
Deduct 774 from 776 and we're left with 2.
Take the next digit (3) from the dividend and append it to 2, then repeat: 23 / 86

Moving on to step 6:
When dividing 23 by 86, we get 0 with a remainder of 23.
Write down 0 as next digit of the result. 
Result so far: 7490.0
Deduct 0 from 23 and we're left with 23.
Since there are no more digits in the dividend, we add a zero to the remainder making it 230, and continue the process.

Moving on to step 7:
230 divided by 86 is 2 with a remainder of 58.
Use 2 as the next digit of our solution. 
Result so far: 7490.2
Subtract 172 from 230 to get 58.
Since there are no more digits in the dividend, we add a zero to the remainder making it 580, and continue the process.

Advancing to step 8:
580 divided by 86 is 6 with a remainder of 64.
Record the quotient 6 as the next digit in the result. 
Result so far: 7490.26
Subtract 516 from 580 to get 64.
Since there are no more digits in the dividend, we add a zero to the remainder making it 640, and continue the process.

On to step 9:
The number 86 fits into 640 7 times, leaving a remainder of 38.
Use 7 as the next digit of our solution. 
Result so far: 7490.267
If we subtract 602 from 640, we get 38.
Since there are no more digits in the dividend, we add a zero to the remainder making it 380, and continue the process.

Let's proceed to step 10:
When dividing 380 by 86, we get 4 with a remainder of 36.
Put 4 as the next digit of the answer. 
Result so far: 7490.2674
If we subtract 344 from 380, we get 36.
Since there are no more digits in the dividend, we add a zero to the remainder making it 360, and continue the process.

Let's proceed to step 11:
The number 86 fits into 360 4 times, leaving a remainder of 16.
Write down 4 as next digit of the result. 
Result so far: 7490.26744
If we take 344 away from 360, we end up with 16.
Since there are no more digits in the dividend, we add a zero to the remainder making it 160, and continue the process.

The final outcome is 7490.26744, with a leftover of 1.6e-05.