Python program to find Prime Numbers between 1 to100.

Find Prime number between 1 to100

Here, in this page we will discuss program to find Prime number between 1 to100 in python .A prime number is an positive integer that has no divisors  except one and itself or can only be exactly divided by the integers 1 and itself without leaving a remainder.
For example n is prime, if n can only be divided by 1 and n. So prime number has two factor one is 1 another is number itself .

The number 1 is neither prime nor composite.

Example: 

  • n=7 
    • divisors of 7 are 1 and 7 itself  so it is a prime number.
Prime number between 1 to 100

Implementation:

  • From 1 to 100 we will start from 2 to check the number of divisors of every number.
  • If a number have only two divisors then it is a Prime number. 

 

Python program for finding the list of all the prime numbers between 1 to 100
#To find the prime numbers between 1 to 100 

li=[] #list of prime numbers will be stored here 

for i in range(2,101):

    f=0

    for j in range(2,i+1):

        if(i!=j and i%j==0): #if any n

            f=1

            break 

    if(f==0):

        li.append(i)

print('Prime numbers between 1 to 100:')

print(*li,sep=' ')
Output:

Prime numbers between 1 to 100:

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97

Optimal Solution to find prime number between 1 to 100 :

  • This method is known as Sieve of Eratosthenes. 
  • Time Complexity: O(n*log(logn)) .
  • Here n is maximum range. 

Python Code:

#To find the prime numbers between 1 to 100 

li=[True]*(101)  #list of prime numbers 

li[1]=False 

li[0]=False

p=2 

while(p*p<=101):

    if(li[p]==True): #if it is a prime number then its multiples will be non-prime

        for i in range(p*p,101,p):

            li[i]=False 

    p=p+1

print('Prime numbers between 1 to 100:')

for i in range(2,101):

    if(li[i]==True):

        print(i, end=' ')
Output:

Prime numbers between 1 to 100:

2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97