In Python 2 / returns only integer part if you use two integers - like int(0.8). You have to use float ie. float(a) or 4.0 (shortly 4.) or * 1.0
print float(4)/5
print 4/float(5)
print 4.0/5
print 4/5.0
print 4./5
print 4/5.
print a*1.0/b # sometimes you can see this method
print a/(b*1.0) # this version need () - without () you get (a/b)*1.0
