C Programming Practice Set 2 – Loops & Number Problems

Loops are one of the most powerful concepts in programming. They allow us to execute a block of code repeatedly without writing the same statements again and again.

In this practice set, you'll solve problems involving loops, number manipulation, and mathematical logic. These exercises strengthen your understanding of for, while, and do...while loops.

Each program includes:

• 🎯 Objective
• 💡 Problem Statement
• 💻 C Program
• ▶ Sample Input
• ✅ Sample Output
• 📚 Explanation

Program 1 — Print Numbers from 1 to N

🎯 Objective

Use a for loop to print numbers from 1 to N.

Program

cCopy
#include <stdio.h>

int main()
{
    int n;

    printf("Enter N: ");
    scanf("%d", &n);

    for(int i = 1; i <= n; i++)
    {
        printf("%d ", i);
    }

    return 0;
}

Sample Input

5

Sample Output

1 2 3 4 5

Explanation

The loop starts from 1 and continues until i becomes equal to n.

Program 2 — Print Numbers from N to 1

Program

cCopy
#include <stdio.h>

int main()
{
    int n;

    scanf("%d", &n);

    for(int i = n; i >= 1; i--)
    {
        printf("%d ", i);
    }

    return 0;
}

Sample Input

5

Sample Output

5 4 3 2 1

Program 3 — Sum of First N Natural Numbers

Program

cCopy
#include <stdio.h>

int main()
{
    int n, sum = 0;

    scanf("%d", &n);

    for(int i = 1; i <= n; i++)
    {
        sum += i;
    }

    printf("Sum = %d", sum);

    return 0;
}

Program 4 — Factorial of a Number

Program

cCopy
#include <stdio.h>

int main()
{
    int n;
    long long factorial = 1;

    scanf("%d", &n);

    for(int i = 1; i <= n; i++)
    {
        factorial *= i;
    }

    printf("%lld", factorial);

    return 0;
}

Sample Input

5

Sample Output

120

Program 5 — Multiplication Table

Program

cCopy
#include <stdio.h>

int main()
{
    int n;

    scanf("%d", &n);

    for(int i = 1; i <= 10; i++)
    {
        printf("%d x %d = %d\n", n, i, n * i);
    }

    return 0;
}

Program 6 — Check Prime Number

Program

cCopy
#include <stdio.h>

int main()
{
    int n, prime = 1;

    scanf("%d", &n);

    if(n <= 1)
    {
        prime = 0;
    }

    for(int i = 2; i <= n / 2 && prime; i++)
    {
        if(n % i == 0)
        {
            prime = 0;
        }
    }

    if(prime)
        printf("Prime");
    else
        printf("Not Prime");

    return 0;
}

Program 7 — Fibonacci Series

Program

cCopy
#include <stdio.h>

int main()
{
    int n;
    int first = 0;
    int second = 1;
    int next;

    scanf("%d", &n);

    for(int i = 1; i <= n; i++)
    {
        printf("%d ", first);

        next = first + second;
        first = second;
        second = next;
    }

    return 0;
}

Sample Input

8

Sample Output

0 1 1 2 3 5 8 13

Program 8 — Reverse a Number

Program

cCopy
#include <stdio.h>

int main()
{
    int number, reverse = 0;

    scanf("%d", &number);

    while(number != 0)
    {
        reverse = reverse * 10 + number % 10;
        number /= 10;
    }

    printf("%d", reverse);

    return 0;
}

Program 9 — Check Palindrome Number

Program

cCopy
#include <stdio.h>

int main()
{
    int number, temp, reverse = 0;

    scanf("%d", &number);

    temp = number;

    while(temp != 0)
    {
        reverse = reverse * 10 + temp % 10;
        temp /= 10;
    }

    if(number == reverse)
        printf("Palindrome");
    else
        printf("Not Palindrome");

    return 0;
}

Sample Input

121

Sample Output

Palindrome

Program 10 — Count Digits in a Number

Program

cCopy
#include <stdio.h>

int main()
{
    int number;
    int count = 0;

    scanf("%d", &number);

    while(number != 0)
    {
        count++;
        number /= 10;
    }

    printf("Digits = %d", count);

    return 0;
}

Sample Input

98765

Sample Output

Digits = 5

⭐ Practice Challenge

Solve these programs on your own before checking the solutions.

1. Print all even numbers from 1 to N.
2. Print all odd numbers from 1 to N.
3. Find the sum of even numbers.
4. Find the sum of odd numbers.
5. Check whether a number is an Armstrong number.
6. Find the greatest digit in a number.
7. Find the smallest digit in a number.
8. Calculate the sum of digits.
9. Print all prime numbers from 1 to N.
10. Print the Fibonacci series using a while loop.

📚 Summary

In this practice set, you learned how to use loops to solve common number-based problems, including:

• Counting
• Factorials
• Prime numbers
• Fibonacci series
• Number reversal
• Palindrome checking
• Digit counting

These programs build strong problem-solving skills and prepare you for more advanced topics like pattern printing and arrays.

🚀 What's Next?

In Practice Set 3 – Pattern Printing, you'll solve interesting pattern problems using nested loops, including:

• Square Patterns
• Triangle Patterns
• Pyramid Patterns
• Number Patterns
• Character Patterns
• Floyd's Triangle
• Pascal's Triangle (Introduction)

Happy Coding with KauraX 💙