Python: Identify nonprime numbers between 1 to 100

Last update on May 24 2025 10:48:34 (UTC/GMT +8 hours)

Find Non-Prime Numbers

Write a Python program to identify non-prime numbers between 1 and 100 (integers). Print the non-prime numbers.

Sample Solution:

Python Code:

# Import the 'math' module to use mathematical functions.
import math

# Define a function 'is_not_prime' to check if a number is not prime.
def is_not_prime(n):
    # Initialize the answer as False.
    ans = False
    
    # Iterate through potential divisors from 2 to the square root of 'n' (inclusive).
    for i in range(2, int(math.sqrt(n)) + 1):
        # If 'n' is divisible by 'i', set the answer to True.
        if n % i == 0:
            ans = True
    
    # Return the final answer.
    return ans

# Print a message indicating the purpose of the following loop.
print("Nonprime numbers between 1 to 100:")

# Use the 'filter' function to create an iterable of nonprime numbers.
# Iterate through the filtered numbers and print each one.
for x in filter(is_not_prime, range(1, 101)):
    print(x)

Sample Output:

Nonprime numbers between 1 to 100:
4
6
8
9
10
12
14
15

..

90
91
92
93
94
95
96
98
99
100

Explanation:

Here is a breakdown of the above Python code:

• Module Import:
• The code imports the "math" module to use mathematical functions, specifically, the square root function.
• Function definition - is_not_prime:
• A function named "is_not_prime()" is defined to check if a given number is not prime.
• The function uses a loop to iterate through potential divisors and sets the answer to True if any divisor is found.
• Printing message:
• A message is printed to indicate the purpose of the following loop.
• Filtering and printing nonprime numbers:
• The "filter()" function is used to create an iterable of nonprime numbers in the range from 1 to 100.
• The iterable is then looped through, and each nonprime number is printed.

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to list all composite numbers between 1 and 100 by checking for non-prime conditions.
• Write a Python program to generate non-prime numbers within a specified range by testing for factors.
• Write a Python program to filter out prime numbers from a range and output the remaining composite numbers.
• Write a Python program to compute and print all non-prime integers between 1 and 100 using a helper function.

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