from math import sqrt
running = 'Y'

while 'Y' in running or 'y' in running:
    #defining numbers
    startn = float(raw_input('What is the starting number'))
    startn2 = startn
    endn = float(raw_input('What is the ending number?'))
    endn2 = endn
    #defining lists
    num = []
    nums = []
    numsq = []
    while startn2 != (endn2+1):
        #just the numbers
        a = int(startn2)
        num.append(a)
        startn2+=1
    startn2 = startn
    print 'numbers without changing are:', num
    while startn2 != (endn2+1):
        #numbers squared
        a = int(startn2*startn2)
        nums.append(a)
        startn2+=1
    startn2 = startn
    print 'numbers squared are:', nums
    while startn2 != (endn2+1):
        #numbers square-rooted
        #Here is my problem, i want to simplify it to about 6 digits e.g. 5.12345
        a = sqrt(startn2)
        numsq.append(a)
        startn2+=1
    startn2 = startn
    print 'numbers square-rooted are:', numsq
    running = raw_input('Try another set? (Y or N)')

>>> round(math.pi, 5)
3.1415899999999999
>>> "%0.5f" % math.pi
'3.14159'
>>> sig_digits = 6
>>> num = 123.456789
>>> "%0.*f" % (sig_digits-len(str(num).split('.')[0]), num)
'123.457'
>>> num = 1.23456789
>>> "%0.*f" % (sig_digits-len(str(num).split('.')[0]), num)
'1.23457'
>>> num = 1234567890
>>> "%0.*f" % (sig_digits-len(str(num).split('.')[0]), num)
'1234567890'
>>>

# representing print formatted floats in a list
 
list_floats = [1/3.0, 1/6.0, 3.124567, 5.01]
 
print list_floats
 
"""
my output (note the typical float representation problem) -->
[0.33333333333333331, 0.16666666666666666, 3.1245669999999999, 5.0099999999999998]
"""
 
# create a new list of floats using round()
list_floats2 = []
for n in list_floats:
    list_floats2.append(round(n, 5))
 
print list_floats2
 
"""
my output (notice we are still dealing with floats) -->
[0.33333000000000002, 0.16667000000000001, 3.1245699999999998, 5.0099999999999998]
"""
 
# to make round() stick for your print
# you have to store the result as a string
list_floats3 = []
for n in list_floats:
    list_floats3.append(str(round(n, 5)))
 
print list_floats3
 
"""
my output -->
['0.33333', '0.16667', '3.12457', '5.01']
"""
 
# or ...
list_floats4 = []
for n in list_floats:
    list_floats4.append("%0.5f" % n)
 
print list_floats4
 
"""
my output -->
['0.33333', '0.16667', '3.12457', '5.01000']
"""