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Square Numbers Ending in 5

📌 Problem Description

Write a program to calculate the square of a number only if its least significant digit (the last digit) is 5.

If the number ends in 5, the program calculates and displays its square. Otherwise, the program informs the user that the number does not end in 5.

💡 Example

Example 1:

Enter the number: 25
Square = 625

Example 2:

Enter the number: 13
The number does not end in 5.

🧠 Algorithm

1. Ask the user to enter an integer.
2. Use the modulo operator (%) to check the last digit of the number.
3. If number % 10 == 5, calculate the square of the number.
4. Display the result.
5. Otherwise, display a message indicating that the number does not end in 5.

💻 Source Code (C)

#include <stdio.h>

int main() {
    int number;

    printf("Enter the number: ");
    scanf("%d", &number);

    if (number % 10 == 5) {
        printf("Square = %d\n", number * number);
    } else {
        printf("The number does not end in 5.\n");
    }

    return 0;
}

📖 Explanation

• scanf("%d", &number); reads an integer entered by the user.
• number % 10 returns the remainder after dividing the number by 10, which identifies its last digit.
• number % 10 == 5 checks whether the last digit is 5.
• number * number calculates the square of the number.
• if-else determines whether the square should be calculated and displayed.

🚀 How to Run

1. Save the program as main.c.
2. Compile the program using GCC:

   gcc main.c -o main
   

3. Run the program:

   ./main
   

   On Windows, run:

   main.exe
   

🎯 Learning Objectives

• Understand conditional statements (if-else).
• Learn how to use the modulo operator (%).
• Practice user input and output in C.
• Apply arithmetic operations to calculate squares.

📝 Notes

This program checks the last digit of an integer before calculating its square. The example uses the C language and is intended for beginners learning conditional statements and arithmetic operators.

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Language: C
Topic: Conditional Statements, Modulo Operator, Arithmetic Operations