n prime numbers in python code example

Example 1: determine if number is prime python

# Time Efficient Primality Check in Python

def primeCheck(n):
    # 0, 1, even numbers greater than 2 are NOT PRIME
    if n==1 or n==0 or (n % 2 == 0 and n > 2):
        return "Not prime"
    else:
        # Not prime if divisable by another number less
        # or equal to the square root of itself.
        # n**(1/2) returns square root of n
        for i in range(3, int(n**(1/2))+1, 2):
            if n%i == 0:
                return "Not prime"
        return "Prime"

Example 2: python program to find n prime numbers

num = 10
for i in range(2,num+1):
    for j in range(2,i):
        if(i%j == 0):
            break
    else:
        print(i)

Example 3: first n prime number finder in python

>>> def getprimes(x):	primes = []	# Loop through 9999 possible prime numbers	for a in range(1, 10000):		# Loop through every number it could divide by		for b in range(2, a):			# Does b divide evenly into a ?			if a % b == 0:				break		# Loop exited without breaking ? (It is prime)		else:			# Add the prime number to our list			primes.append(a)		# We have enough to stop ?		if len(primes) == x:			return primes		>>> getprimes(5)[1, 2, 3, 5, 7]>>> getprimes(7)[1, 2, 3, 5, 7, 11, 13]

Example 4: prime numbers upto n in python

lower = int(input("Enter lower range: "))  
upper = int(input("Enter upper range: "))  
  
for num in range(lower,upper + 1):  
   if num > 1:  
       for i in range(2,num):  
           if (num % i) == 0:  
               break  
       else:  
           print(num)