Checking Whether a Number is a Trendy Number in Python

A trendy number is defined as a three-digit number where the middle digit is divisible by 3. In this blog post, we’ll write a Python program to determine whether a given number is a trendy number or not.

Problem Description

Given an integer n, the program should:

1. Check if n is a three-digit number.
2. Verify if the middle digit of n is divisible by 3.
3. Output “Trendy Number” if both conditions are met; otherwise, output “Not a Trendy Number.”

Approach

1. Check Number of Digits: Convert the number to a string to check if it has exactly three digits.
2. Middle Digit Extraction: The middle digit can be accessed using string indexing.
3. Divisibility Check: Convert the middle digit back to an integer and check if it’s divisible by 3.
4. Print Result: Based on the checks, print the appropriate message.

Python Implementation

def is_trendy_number(n):
    n_str = str(n)

    # Check if the number has exactly 3 digits
    if len(n_str) == 3:
        middle_digit = int(n_str[1])

        # Check if the middle digit is divisible by 3
        if middle_digit % 3 == 0:
            print("Trendy Number")
        else:
            print("Not a Trendy Number")
    else:
        print("Not a Trendy Number")

# Input Handling
n = int(input())

# Check if the number is a trendy number
is_trendy_number(n)

Explanation

• String Conversion: The number is converted to a string to easily access and check the number of digits and the middle digit.
• Middle Digit Check: The middle digit is accessed using n_str[1] and checked for divisibility by 3.
• Conditional Output: If the conditions for a trendy number are met, “Trendy Number” is printed; otherwise, “Not a Trendy Number” is printed.

Test Cases

Let’s validate the program with some sample inputs:

# Test Case 1
# Input: 791
# Expected Output: Trendy Number
is_trendy_number(791)

# Test Case 2
# Input: 153
# Expected Output: Not a Trendy Number
is_trendy_number(153)

# Test Case 3
# Input: 945
# Expected Output: Trendy Number
is_trendy_number(945)

# Test Case 4
# Input: 29
# Expected Output: Not a Trendy Number
is_trendy_number(29)

# Test Case 5
# Input: 812
# Expected Output: Not a Trendy Number
is_trendy_number(812)

Conclusion

This simple program efficiently checks whether a given number is a trendy number by validating its digit length and checking the divisibility of the middle digit. It’s a straightforward approach suitable for beginners to understand basic string manipulation and conditional logic in Python. Try it out with different numbers to see if they are trendy or not!