The prime factors of 13195 are 5, 7, 13 and 29.
What is the largest prime factor of the number 600851475143 ?
#don't forget 2,3,5,7. this function doesn't deliver those as output.
def is_prime(b): #checks a number greater than 7 to see if it is prime and
returns if is.
if b % 2 != 0 and b % 3 != 0 and b % 5 != 0 and b % 7 != 0:
print b,
def factor(num):
x = num
b = 1
c = num
while b <= c: #starts at 1 and searches all the numbers up to the
number you put in
if x % b == 0:
is_prime(b)
b += 1
else:
b += 1
print "Don't forget to consider primes 2, 3, 5, and 7\n"
#600851475143
#shows what numbers in given range are prime
'''
def is_prime(b):
return [2,3,5,7] + [x for x in xrange(3, 10000, 2) if x % 2 != 0 and x % 3
!= 0 and x % 5 != 0 and x % 7 != 0]
'''
I'm looking for some help with this problem. I realize my code is inefficient
for such a big number, and also I'm not quite sure it works perfectly in and of
itself.
My current reasoning was something of this sort: Find all the factors of a
number, then reduce them to just the prime factors and you can then multiply
them together to get that number thus having the prime factors. I need a lot
of help haha. Thanks in advance everyone. If anyone has a good resource to
point me to other than the open book project and dive into python it would be
much appreciated. Would it be useful for me to buy a book, and if so what are
some easily accessible ones? I feel dive into python is just too advanced for
me. I understand a lot of the teachings, but the examples seem unwieldy and
esoteric.
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