Python Program to Check Prime Number
Python Program to Check Prime Number
# Python program to check if the input number is prime or not
num = 407
# 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")
num = 407
# 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")
output:
407 is not a prime number
11 times 37 is 407
11 times 37 is 407
In this program, variable num is checked if it's prime or not.
Numbers less than or equal to 1 are not prime numbers. Hence, we only
proceed if the num is greater than 1.
We check if num is exactly divisible by any number from 2
to num - 1. If we find a factor in that range, the number is not prime.
Else the number is prime.
We can decrease the range of numbers where we look for factors.
In the above program, our search range is from 2 to num - 1.
We could have used the range, [2, num / 2] or [2, num
** 0.5]. The later range is based on the fact that a composite number
must have a factor less than square root of that number; otherwise the
number is prime.
You can change the value of variable num in the above source code and test for other integers (if you want).
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