We're dividing 621389 by 15 
We want to divide 621389 by 15.

On to step 1:
15 goes into 6 0 times with a remainder of 6.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 6 leaves us with 6.
Take the next digit (2) from the dividend and append it to 6, then repeat: 62 / 15

Moving on to step 2:
15 goes into 62 4 times with a remainder of 2.
The number 4 becomes the next digit in our result. 
Result so far: 4.0
If we subtract 60 from 62, we get 2.
Include the next digit (1) from the dividend after 2, then repeat: 21 / 15

Advancing to step 3:
When dividing 21 by 15, we get 1 with a remainder of 6.
The number 1 becomes the next digit in our result. 
Result so far: 41.0
Subtracting 15 from 21 leaves us with 6.
Take the next digit (3) from the dividend and append it to 6, then repeat: 63 / 15

Moving on to step 4:
The number 15 fits into 63 4 times, leaving a remainder of 3.
Put 4 as the next digit of the answer. 
Result so far: 414.0
The remainder is 3 after subtracting 60 from 63.
Include the next digit (8) from the dividend after 3, then repeat: 38 / 15

Advancing to step 5:
The number 15 fits into 38 2 times, leaving a remainder of 8.
The next digit of our result is 2. 
Result so far: 4142.0
Deduct 30 from 38 and we're left with 8.
Take the next digit (9) from the dividend and append it to 8, then repeat: 89 / 15

On to step 6:
The number 15 fits into 89 5 times, leaving a remainder of 14.
Write down 5 as next digit of the result. 
Result so far: 41425.0
The remainder is 14 after subtracting 75 from 89.
Since there are no more digits in the dividend, we add a zero to the remainder making it 140, and continue the process.

On to step 7:
If we divide 140 by 15, we get 9 and a remainder of 5.
The number 9 becomes the next digit in our result. 
Result so far: 41425.9
If we take 135 away from 140, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Moving on to step 8:
If we divide 50 by 15, we get 3 and a remainder of 5.
Use 3 as the next digit of our solution. 
Result so far: 41425.93
If we take 45 away from 50, we end up with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

Going ahead to step 9:
15 can be fit into 50 3 times, resulting in a remainder of 5.
Put 3 as the next digit of the answer. 
Result so far: 41425.933
Deduct 45 from 50 and we're left with 5.
Since there are no more digits in the dividend, we add a zero to the remainder making it 50, and continue the process.

The quotient of the division is 41425.933, and the remainder is 0.0005.