Here, we want to express the given fraction as a decimal by the use of long division
We start by writing the long division sign
We place 5 on the left hand side outside and place 4 inside the long division sign
Now, as we know, 4 cannot divide 5 wholly as it is less than 5
We simply add a 0 at the top of the long division symbol, with a decimal point after it.
Concurrently, we place a zero after 4
Hence we have 40 inside the long division
Then we can divide 40 by 5 to get 8
The 8 now comes after the decimal point
Hence, our answer is 0.8
Pictorally, we can have the representation as follows;