158539 ÷ 40 
We want to divide 158539 by 40.

Step 1:
1 divided by 40 is 0 with a remainder of 1.
The next digit of our result is 0. 
Result so far: 0.0
If we take 0 away from 1, we end up with 1.
Grab the next digit (5) from the dividend, add it to 1, then carry on: 15 / 40

Moving on to step 2:
40 can be fit into 15 0 times, resulting in a remainder of 15.
Write down 0 as next digit of the result. 
Result so far: 0.0
Subtracting 0 from 15 leaves us with 15.
Bring next digit (8) of the dividend behind the 15 and repeat the process: 158 / 40

Moving on to step 3:
When dividing 158 by 40, we get 3 with a remainder of 38.
The next digit of our result is 3. 
Result so far: 3.0
Subtracting 120 from 158 leaves us with 38.
Grab the next digit (5) from the dividend, add it to 38, then carry on: 385 / 40

Advancing to step 4:
When dividing 385 by 40, we get 9 with a remainder of 25.
Use 9 as the next digit of our solution. 
Result so far: 39.0
The remainder is 25 after subtracting 360 from 385.
Append the next digit (3) from the dividend to 25 and continue with: 253 / 40

Step 5:
253 divided by 40 is 6 with a remainder of 13.
The number 6 becomes the next digit in our result. 
Result so far: 396.0
If we take 240 away from 253, we end up with 13.
Take the next digit (9) from the dividend and append it to 13, then repeat: 139 / 40

Advancing to step 6:
When dividing 139 by 40, we get 3 with a remainder of 19.
Use 3 as the next digit of our solution. 
Result so far: 3963.0
The remainder is 19 after subtracting 120 from 139.
Since there are no more digits in the dividend, we add a zero to the remainder making it 190, and continue the process.

Moving on to step 7:
If we divide 190 by 40, we get 4 and a remainder of 30.
The number 4 becomes the next digit in our result. 
Result so far: 3963.4
Deduct 160 from 190 and we're left 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.

Moving on to step 8:
300 divided by 40 is 7 with a remainder of 20.
The next digit of our result is 7. 
Result so far: 3963.47
The remainder is 20 after subtracting 280 from 300.
Since there are no more digits in the dividend, we add a zero to the remainder making it 200, and continue the process.

Moving on to step 9:
When dividing 200 by 40, we get 5 with a remainder of 0.
The number 5 becomes the next digit in our result. 
Result so far: 3963.475
If we subtract 200 from 200, 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.

Advancing to step 10:
If we divide 0 by 40, we get 0 and a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 3963.475
Deduct 0 from 0 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.

Advancing to step 11:
If we divide 0 by 40, we get 0 and a remainder of 0.
Put 0 as the next digit of the answer. 
Result so far: 3963.475
If we take 0 away from 0, we end up 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.

Our division results in 3963.475 with a remaining 0.0.