Use python check if this number is a prime or not?

Question

I got an hexadecimal

number = C847923CE24DE8B7CA66AB9620BAF1831FE65EA0D9A2928D6D75B12C567F6C2586ED07AE0EE5C8ECD8793F1683AF1893C0BE521A10F69E6DC951DC7E2CB47E8B

It should be equal to

10489492484628552513045989867681469503774243086255660470449316956846449417667713853937696810038768145686753348376338135274255531844743941964455973060116107

I tried this https://www.programiz.com/python-programming/online-compiler/?ref=374cc95b

But got this error:

Traceback (most recent call last): File "", line 4, in OverflowError: range() result has too many items

You need to show us the code that is giving the error, and the link you provide doesn't show it. Please include the code with the problem *in your question* as text, not a link (even if it works) and not a picture (because we can't run it). As your question stands, you are asking us to imagine what you have written and then find the problem in it. — BoarGules, Mar 26 '20 at 19:47
There are modules that do prime numbers. This is a job for pip. If you're just asking about the hex number, https://stackoverflow.com/questions/209513/convert-hex-string-to-int-in-python — Kenny Ostrom, Mar 26 '20 at 19:49
The error message you report (*range result has too many items*) indicates that you are running Python 2. At this stage you should not be investing effort in learning Python 2. — BoarGules, Mar 26 '20 at 19:57

score 4 · Answer 1 · answered Mar 26 '20 at 19:51

4

If you are ok using a library to check whether the number is prime or not (and your questions isn't about how to write an efficient prime-checker on your own), what about the following:

>>> import sympy
>>> num = int('C847923CE24DE8B7CA66AB9620BAF1831FE65EA0D9A2928D6D75B12C567F6C2586ED07AE0EE5C8ECD8793F1683AF1893C0BE521A10F69E6DC951DC7E2CB47E8B', 16)
# 10489492484628552513045989867681469503774243086255660470449316956846449417667713853937696810038768145686753348376338135274255531844743941964455973060116107L
>>> sympy.isprime(num)
# False

Regarding converting a hex number to a normal (base ten) number, you can do:

>>> int('A', 16)
10

Where the second arg is the base of the input number.

answered Mar 26 '20 at 19:51

David542

104,438
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Thanks David542, using a library can work out , pip3 install sympy. – eoffer Mar 27 '20 at 05:06
Python also have a math library to factor out this large number ? – eoffer Mar 27 '20 at 05:19
@eoffer yea...if you look hard enough you can pretty much find anything. Three good math libraries are https://www.sympy.org/en/index.html, https://numpy.org/, and Scipy. – David542 Mar 27 '20 at 17:01

eoffer · Answer 2 · 2020-03-27T05:19:51.713

But I also need an efficient prime-checker of my code: why below code can not ihandle large numbers ?

# Program to check if a number is prime or not

num = 407

# To take input from the user
#num = int(input("Enter a number: "))

# prime numbers are greater than 1
if num > 1:
# check for factors
for i in range(2,num):
   if (num % i) == 0:
       print(num,"is not a prime number")
       print(i,"times",num//i,"is",num)
       break
  else:
   print(num,"is a prime number")

  # if input number is less than
  # or equal to 1, it is not prime
  else:
     print(num,"is not a prime number")

Use python check if this number is a prime or not?

2 Answers2