In the first 20/3, the system will think that this is the operation of shaping data, and the result is 6. Then, when the plastic data is assigned to the real data, the plastic data will be forcibly converted into the real data. So the output is 6.000000.

At the same time, you also made a mistake. All the real data of a computer are stored in binary form, and different machines and compilers have different binary digits for the same data type. For example:

Int data is generally 2 bits, but there are also 4 bits. So don't be confused by part of the textbook.