Algorithm


  1. Initialize: Set the variable is_prime to True.
  2. Special Cases:
  3. If the number is less than or equal to 1, set is_prime to False.
  4. If the number is 2, it's a prime number, so no further checks are needed.
  5. If the number is even (other than 2), set is_prime to False.
  6. Divisibility Check:
    • Iterate from 3 to the square root of the number (inclusive).
    • If the number is divisible by any of these values, set is_prime to False.
    • Result:
      • If is_prime is still True after the above checks, the number is prime.

 

Code Examples

#1 Example- Python Programing Prime Number in Python using For Loop

Code - Python Programming

# Prime Number Program in Python using For Loop
 
a=int(input("Enter number: "))
k=0
for i in range(2,a//2+1):
    if(a%i==0):
        k=k+1
if(k<=0):
    print("Number is prime")
else:
    print("Number isn't prime">
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Input

x
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cmd
Enter number: 7

Output

x
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cmd
Number is prime

#2 Example- Python programing Prime Number Program in Python using Recursion

Code - Python Programming

def check(n, div = None):
    if div is None:
        div = n - 1
    while div >= 2:
        if n % div == 0:
            print("Number not prime")
            return False
        else:
            return check(n, div-1)
    else:
        print("Number is prime")
        return 'True'
n=int(input("Enter number: "))
check(n)
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Input

x
+
cmd
1. Enter number: 13
2. Enter number: 30

Output

x
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cmd
1. Number is prime
2. Number not prime

#3 Example- Python Programing Prime Number Program in Python using Recursion

Code - Python Programming

r=int(input("Enter upper limit: "))
for a in range(2,r+1):
    k=0
    for i in range(2,a//2+1):
        if(a%i==0):
            k=k+1
    if(k<=0):
        print(a>
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#4 Example- Python Programing Prime Number Program in Python using Sieve of Eratosthenes

Code - PHP Programming

n=int(input("Enter upper limit of range: "))
sieve=set(range(2,n+1))
while sieve:
    prime=min(sieve)
    print(prime,end="\t")
    sieve-=set(range(prime,n+1,prime))
 
print()
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Demonstration


Python Programing Example to Check Prime Number-DevsEnv