for and while challenges
1. Print numbers from 1 to 10.
public class printnum{
public static void main(String[] args){
System.out.println("Print numbers from 1 to 10");
for(int i=1;i<=10;i++){
System.out.print(i + " ");
}
}
}
OUTPUT:
2. Print even numbers between 1 and 20.
class evennum {
public static void main(String[] args){
System.out.println("Print even numbers between 1 and 20");
for(int i=2;i<=20;i+=2){
System.out.print(i + " ");
}
}
OUTPUT:
3. Print the multiplication table of a given numbers.
class multiplicationtable {
public static void main(String[] args){
int n=1, m=7;
while (n<=10){
System.out.println(n +" X "+ m +" = " + (n*m));
n++;
}
}
}
OUTPUT:
4. Print the sum of the first 10 natural numbers.
import java.util.Scanner;
class naturalnum {
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
System.out.println("Enter the number of N: ");
int n=sc.nextInt();
int N;
int sum=0;
for( int i=1;i<=n;i++){
sum += i;
}
System.out.println("Sum of the first "+ n + " natural numbers :" +(sum));
sc.close();
}
}
OUTPUT:
5. Print the sum of the first N even numbers.
import java.util.Scanner;
class sumeven {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
System.out.println("Enter the number N:");
int n=sc.nextInt();
int sum=0;
for(int i=1;i<=n;i++)
sum +=2*i;
System.out.println("Sum of the first " + n + " even numbers = " +sum );
}
}
OUTPUT:
6. Print the factorial of a number.
class factorialnum {
public static void main(String args[]){
int factorial=1;
int i=1;
while(i<=5) {
factorial *= i;
i++;
}
System.out.println("Factorial = " +factorial);
}
}
OUTPUT:
7. Print the reverse of a number (e.g., 123 - 321).
public class reverse{
public static void main(String[] args){
int i=234;
int rev=0;
while(i>0){
int num=i%10;
rev=rev*10 +num;
i=i/10;
}
System.out.println("Print the numbers in reverse: " + rev);
}
}
OUTPUT:
8. Print the sum of digits of a number.
import java.util.Scanner;
public class digitsum {
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
System.out.println("Enter the digits:");
int num=sc.nextInt();
int sum=0;
for( ;num>0;num /=10 ){
sum +=num%10;
}
System.out.println("Sum of digits : " + sum );
sc.close();
}
}
OUTPUT:
9. Print the product of digits of a number.
import java.util.Scanner;
class digitproduct {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
System.out.println("Enter the Digits:");
int digit=sc.nextInt();
int product=1;
while(digit>0){
int num=digit%10;
product *=num;
digit=digit/10;
}
System.out.println("The product of digit is = " +product);
sc.close();
}
}
OUTPUT:
10. Check if a number is a palindrome (e.g., 121-yes).
class palindrome {
public static void main(String[] args){
int x=464; int temp=x; int rev=0;
while(x>0){
int digit=x%10;
rev=rev * 10 + digit;
x= x/10;
}
System.out.println("rev = " + rev);
if(temp==rev){
System.out.println("It is palindrome");
}
else{
System.out.println("It is not palindrome");
}
}
}
OUTPUT:
11. Check if a number is an Armstrong number (e.g., 153).
class armstrong {
public static void main(String[] args){
int x=153, sum=0;
int temp = x;
for(;x>0;x=x/10){
int digit= x%10;
sum = sum + (digit * digit * digit);
System.out.println("Sum of cubes = " + sum);
}
if(temp==sum){
System.out.println(sum + " is an armstrong number.");
}
else{
System.out.println(sum + " is not an armstrong number.");
}
}
}
OUTPUT:
12. Print the Fibonacci series up to N terms.
import java.util.Scanner;
class fibonacci {
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
System.out.println("Enter the terms: ");
int n=sc.nextInt();
int a=0, b=1;
for(int x=1;x<=n;x++){
System.out.print(a + " ");
int c=a+b;
a=b;
b=c;
}
}
}
OUTPUT:
13. Count the number of digits in a number.
class countdigit{
public static void main(String[] args){
int digit,count=0;
for(digit=4567;digit>0;digit=digit/10){
count++;
}
System.out.println("Count the digits : " + count );
}
}
OUTPUT:
14. Find the largest digit in a number.
import java.util.Scanner;
class largestdigit {
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
System.out.println("Enter the numbers: ");
int num=sc.nextInt();
int largest=0;
while(num>0){
int digit=num%10;
if(digit>largest){
largest=digit;
}
num = num/10;
}
System.out.println("Largest digits : " + largest);
}
}
OUTPUT:
15. Find the smallest digit in a number.
import java.util.Scanner;
class largestdigit {
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
System.out.println("Enter the numbers: ");
int num=sc.nextInt();
int smallest=9;
for(;num>0;num = num/10){
int digit=num%10;
if(digit<smallest){
smallest=digit;
}
}
System.out.println("Smallest digits : " + smallest);
}
}
OUTPUT:
16. Print a square pattern of * (e.g.,5*5).
import java.util.Scanner;
class patternsquare {
public static void main(String[] args){
Scanner sc=new Scanner(System.in);
System.out.println("Enter the terms N:");
int n=sc.nextInt();
for(int i=1;i<=n;i++){
for(int j=1;j<=n;j++){
System.out.print("*");
}
System.out.println();
}
}
}
OUTPUT:
17. Print a triangle pattern of *.
import java.util.Scanner;
class patterntriangle {
public static void main (String[] args){
Scanner sc=new Scanner(System.in);
System.out.println("Enter the term N: ");
int n=sc.nextInt();
int i=1;
while(i<=5) {
int j=1;
while(j<=i){
System.out.print("*");
j++;
}
System.out.println();
i++;
}
}
}
OUTPUT:
