1558172 ÷ 643 
We want to divide 1558172 by 643.

On to step 1:
643 goes into 1 0 times with a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
Subtract 0 from 1 to get 1.
Take the next digit (5) from the dividend and append it to 1, then repeat: 15 / 643

Moving on to step 2:
15 divided by 643 is 0 with a remainder of 15.
Write down 0 as next digit of the result. 
Result so far: 0.0
Deduct 0 from 15 and we're left with 15.
Grab the next digit (5) from the dividend, add it to 15, then carry on: 155 / 643

Advancing to step 3:
When dividing 155 by 643, we get 0 with a remainder of 155.
The next digit of our result is 0. 
Result so far: 0.0
Subtracting 0 from 155 leaves us with 155.
Take the next digit (8) from the dividend and append it to 155, then repeat: 1558 / 643

Let's proceed to step 4:
If we divide 1558 by 643, we get 2 and a remainder of 272.
Use 2 as the next digit of our solution. 
Result so far: 2.0
Subtract 1286 from 1558 to get 272.
Take the next digit (1) from the dividend and append it to 272, then repeat: 2721 / 643

Step 5:
The number 643 fits into 2721 4 times, leaving a remainder of 149.
Write down 4 as next digit of the result. 
Result so far: 24.0
The remainder is 149 after subtracting 2572 from 2721.
Include the next digit (7) from the dividend after 149, then repeat: 1497 / 643

Advancing to step 6:
The number 643 fits into 1497 2 times, leaving a remainder of 211.
Put 2 as the next digit of the answer. 
Result so far: 242.0
Subtract 1286 from 1497 to get 211.
Fetch the next digit (2) from the dividend, attach it to 211 and continue: 2112 / 643

Advancing to step 7:
When dividing 2112 by 643, we get 3 with a remainder of 183.
The number 3 becomes the next digit in our result. 
Result so far: 2423.0
If we take 1929 away from 2112, we end up with 183.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1830, and continue the process.

Let's proceed to step 8:
1830 divided by 643 is 2 with a remainder of 544.
Write down 2 as next digit of the result. 
Result so far: 2423.2
Subtract 1286 from 1830 to get 544.
Since there are no more digits in the dividend, we add a zero to the remainder making it 5440, and continue the process.

Step 9:
643 can be fit into 5440 8 times, resulting in a remainder of 296.
Put 8 as the next digit of the answer. 
Result so far: 2423.28
Subtracting 5144 from 5440 leaves us with 296.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2960, and continue the process.

Advancing to step 10:
643 goes into 2960 4 times with a remainder of 388.
Put 4 as the next digit of the answer. 
Result so far: 2423.284
If we subtract 2572 from 2960, we get 388.
Since there are no more digits in the dividend, we add a zero to the remainder making it 3880, and continue the process.

On to step 11:
643 goes into 3880 6 times with a remainder of 22.
The next digit of our result is 6. 
Result so far: 2423.2846
The remainder is 22 after subtracting 3858 from 3880.
Since there are no more digits in the dividend, we add a zero to the remainder making it 220, and continue the process.

On to step 12:
643 goes into 220 0 times with a remainder of 220.
The next digit of our result is 0. 
Result so far: 2423.2846
Subtracting 0 from 220 leaves us with 220.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2200, and continue the process.

Let's proceed to step 13:
643 can be fit into 2200 3 times, resulting in a remainder of 271.
Write down 3 as next digit of the result. 
Result so far: 2423.284603
The remainder is 271 after subtracting 1929 from 2200.
Since there are no more digits in the dividend, we add a zero to the remainder making it 2710, and continue the process.

Let's proceed to step 14:
When dividing 2710 by 643, we get 4 with a remainder of 138.
The number 4 becomes the next digit in our result. 
Result so far: 2423.2846034
Subtracting 2572 from 2710 leaves us with 138.
Since there are no more digits in the dividend, we add a zero to the remainder making it 1380, and continue the process.

Advancing to step 15:
If we divide 1380 by 643, we get 2 and a remainder of 94.
Put 2 as the next digit of the answer. 
Result so far: 2423.28460342
Subtract 1286 from 1380 to get 94.
Since there are no more digits in the dividend, we add a zero to the remainder making it 940, and continue the process.

The final outcome is 2423.28460342, with a leftover of 9.4e-08.