Why does this return same memory address?

Question

a = 5
b = 5
print(id(a))
print(id(b))
print(id(5))

Answer 1

Both variables a and b reference to the same object of class int - 5.

Python cashes small integers to improve performance and memory consumption.

To see this you can run the next code:
import sys
a = 5
print(sys.getrefcount(5)) # some count
b = 5
print(sys.getrefcount(5)) # count + 1

Answer 2

Read about immutability in python..

Edit:
https://www.tutorialspoint.com/What-is-immutable-in-Python