Why does the interpreter hang when evaluating the expression?

Question

Here's my experiment:

$ python
Python 2.7.5 (default, Feb 19 2014, 13:47:28) 
[GCC 4.8.2 20131212 (Red Hat 4.8.2-7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> a = 3
>>> while True:
...   a = a * a
... 
^CTraceback (most recent call last):
  File "<stdin>", line 2, in <module>
KeyboardInterrupt
>>> a
(seems to go on forever)

I understand that the interpreter looped forever at the "while True: " part, but why did it get stuck evaluating a?

Answer 1

a is now a really large number and it takes a while to print. Print a in the loop and you'll see it gets really big, this is just a fraction of how large it is if you omit the print, because print takes time to execute. Also, note a=1 always quickly returns 1.