Python LCD

# Format your inputs with a : and then a space,
# it makes them nicer to read :)
a = int(input("Enter the first denominator: "))
b = int(input("Enter the second denominator: "))

# Separate your code that "arranges the world"
# to avoid repeating your "main logic"
if a > b:
    x = a
    y = b
else:
    x = b
    y = a

# This is the "main logic"
# because we already figured out whether a or b
# was the biggest, we don't have to think about
# it again here.
factor = 1
while x * factor % y != 0:
    factor += 1

# Python's "string interpolation", a fancy way
# for saying, shoving one string into another,
# makes everything a bit easier to read :)
lcd = x * factor
print "The LCD of %d and %d is %d" % (a, b, lcd)