Java Program to Print Triangular Number Series 1 3 6 10 15 …N

Java Program to Print Triangular Number Series 1 3 6 10 15 …N

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In the previous article, we have discussed about Java Program to Print Cube Number Series 1 8 27 64 … N

In this article we are going to see how to print Triangular number series 1 3 6 10 15 …N  by using Java programming language.

Java Program to print Triangular Number Series 1 3 6 10 15 …N

On observing the pattern carefully, we can see the numbers in the series are triangular number.

Example:

n*(n+1))/2)

i.e. (1*(1+1))/2 = 2/2 = 1

(2*(2+1))/2 =6/2 = 3

(3*(3+1))/2 =12/2 = 6

Let’s see different ways to print Triangular number series 1 3 6 10 15 …N

Method-1: Java Program to Print Triangular Number Series 1 3 6 10 15 …N By Using For Loop

Approach: 

  • Declare an int variable say ‘n’ which holds the nth value of the series
  • Create Scanner class object.
  • Prompt the user to enter a number as value of n.
  • Use a for loop from i=1 to i<=n
  • Inside for loop, Print the result as i*(i+1))/2)

Program:

import java.util.*;
public class Main
{
    public static void main(String[] args)
   {
        //Scanner class object created
        Scanner s = new Scanner(System.in);
        //taking input of 'n' value from user
        System.out.println("Enter the nth value of the series:");
        int n=s.nextInt();
        //printing the series by using for loop
        for(int i = 1; i<=n; i++)
        {
             System.out.print(( i*(i+1)/2)+ " ");
        }
   }
}

Output:

Enter the nth value of the series:
10
1 3 6 10 15 21 28 36 45 55

Method-2: Java Program to Print Triangular Number Series 1 3 6 10 15 …N By Using While Loop

Approach:

  • Declare an int variable say ‘n’ which holds the nth value of the series
  • Create Scanner class object.
  • Prompt the user to enter a number as value of n.
  • Use a while loop from i=1 to i<=n
  • Inside while loop, Print the result as i*(i+1))/2)

Program:

import java.util.*;
public class Main
{
   public static void main(String[] args)
   {
    //Scanner class object created
        Scanner s = new Scanner(System.in);
        //taking input of 'n' value from user
        System.out.println("Enter the the nth value of the series:");
        int n=s.nextInt();
        //printing the series by using for loop
        int i = 1;
    	while(i<=n)
        {
             System.out.print((( i*(i+1))/2)+ " ");
            i++;
        }
   }
}

Output:

Enter the the nth value of the series:
10
1 3 6 10 15 21 28 36 45 55

Method-3: Java Program to Print Triangular Number Series 1 3 6 10 15 …N By Using User Defined Method

Approach:

  • The same logic as method 1 but this time we are moving the for inside a user-defined method
  • Create Scanner class object.
  • Prompt the user to enter a number as value of n.
  • Use a for loop from i=1 to i<=n
  • Print the result as i*(i+1))/2)

Program:

import java.util.*;
public class Main 
{
    public static void main(String[] args)
   {
        //Scanner class object created
        Scanner s = new Scanner(System.in);
        //taking input of 'n' value from user
        System.out.println("Enter the nth value of the series:");
        int n=s.nextInt();
        // method call, to print the series
        m1(n);
   }
    public static void m1(int n)
    {
        //printing the series by using for loop
        for(int i = 1; i<=n; i++)
        {
          System.out.print(((i*(i+1))/2) + " ");
        }
    }
}

Output:

Enter the nth value of the series:
10
1 3 6 10 15 21 28 36 45 55

Are you new to the java programming language? We recommend you to ace up your practice session with these Basic Java Programs Examples

Answer these:

  1. Write a program to print following 1 3 6 10 15 21 28 sequence using for loop?
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  5. Write a program to find sum of the factors in triangular numbers for a given input?
  6. Find n th term of series 1 3 6 10 15 21 in java?
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