20//6 should be 3.0 but why the answer is 3 only which is integer.

Question

confusion between integer and float

Answer 1

Probably because the result of an integer division between two integers is always an integer. The result of 20//3.5 will be a float.

Answer 2

In the example above, 20 % 6 will return 2, because 3*6+2 is equal to 20.