raw_input
returns a string not an integer:
So,
>>> 1 <= "4" <= 20
False
Use int()
:
i = int(raw_input('>> '))
Use just if
, if you're only taking a single input from user:
if 1 <= i <= 20 :
print "Ok adding %d to numbers set: " % i
numbers.append(i)
print "Okay the numbers set is now: " , numbers
Use while
for multiple inputs:
i = int(raw_input('>> '))
numbers = []
while 1 <= i <= 20 :
print "Ok adding %d to numbers set: " % i
numbers.append(i)
i = int(raw_input('>> ')) #asks for input again
print "Okay the numbers set is now: " , numbers