C Exercises: Check whether a given number is an ugly number

Last update on August 05 2025 12:55:39 (UTC/GMT +8 hours)

1. Ugly Number Variants

Write a program in C to check whether a given number is an ugly number or not.

Test Data
Input an integer number: 25

Sample Solution:

C Code:

#include <stdio.h>
#include <string.h>

int main()
{
    int n, x = 0; // Declaration of variables 'n' and 'x' to store the input number and flag respectively
    printf("\n\n Check whether a given number is an ugly number:\n");
    printf("----------------------------------------------------\n");
    printf("Input an integer number: ");
    scanf("%d", &n); // Read an integer from the user and store it in variable 'n'

    if (n <= 0) {
        printf("Input a correct number."); // If the entered number is less than or equal to zero, prompt the user to input a correct number
    }

    while (n != 1) { // Loop to check if the number is an ugly number
        if (n % 5 == 0) {
            n /= 5; // If the number is divisible by 5, divide it by 5
        } else if (n % 3 == 0) {
            n /= 3; // If the number is divisible by 3, divide it by 3
        } else if (n % 2 == 0) {
            n /= 2; // If the number is divisible by 2, divide it by 2
        } else {
            printf("It is not an ugly number.\n"); // If the number is not divisible by 2, 3, or 5, it's not an ugly number
            x = 1; // Set flag 'x' to 1 to indicate it's not an ugly number
            break; // Exit the loop
        }
    }

    if (x == 0) { // Check if the flag 'x' is still 0 after the while loop
        printf("It is an ugly number.\n"); // If 'x' is 0, then it's an ugly number
    }
}

Sample Output:

Input an integer number: 25                                                                              
It is an ugly number. 

Visual Presentation:

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to check if a number is ugly and then print its prime factors.
• Write a C program to generate the first n ugly numbers using dynamic programming.
• Write a C program to test if a number remains ugly after removing its trailing zeros.
• Write a C program to count the frequency of ugly numbers in a given range.

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