In the previous article, we have discussed Python Program to Find Sum of Series 1-2+3-4+5…+N

Given a number N and the task is to find the triangular number series** (1 3 6 10 15 …N)** until the given number.

**int() function in Python:**

The int() function is used to transform a value into an integer number.

**Examples:**

**Example1:**

**Input:**

Given Number = 8

**Output:**

The Triangular series until the given number{ 8 } is : 1 3 6 10 15 21 28 36

**Example2:**

**Input:**

Given Number = 15

**Output:**

The Triangular series until the given number{ 15 } is : 1 3 6 10 15 21 28 36 45 55 66 78 91 105 120

## Program to Print Triangular Number series 1 3 6 10 15 …N in Python

Below are the ways to find the triangular number series** (1 3 6 10 15 …N)** until the given number N :

### Method #1: Using While Loop (Static Input)

**Approach:**

- Give the number N as static input and store it in a variable.
- Take a variable say
**k**and initialize its value with 1. - Loop until the value of
**k**is less than or equal to the given number using the while loop. - Inside the loop, multiply the value of k with k+1 and divide the result by 2 and convert it into an integer using the int() function.
- Store it in a variable say
**p**. - Print the above result (
**p**) separated by spaces to get the triangular series until the given number. - Increment the value of
**k**by 1 and store it in the same variable**k**. - The Exit of the Program.

**Below is the implementation:**

# Give the number N as static input and store it in a variable. gvn_numb = 8 # Take a variable say k and initialize its value with 1. k = 1 print("The Triangular series until the given number{", gvn_numb, "} is :") # Loop until the value of k is less than or equal to the given number using the while loop. while(k <= gvn_numb): # Inside the loop, multiply the value of k with k+1 and divide the result by 2 and # convert it into an integer using the int() function. # Store it in a variable say p. p = int((k*(k+1))/2) # Print the above result (p) separated by spaces to get the triangular series until # the given number. print(p, end=" ") # Increment the value of k by 1 and store it in the same variable k. k += 1

**Output:**

The Triangular series until the given number{ 8 } is : 1 3 6 10 15 21 28 36

### Method #2: Using While loop (User Input)

**Approach:**

- Give the number N as user input using the int(input()) function and store it in a variable.
- Take a variable say
**k**and initialize its value with 1. - Loop until the value of
**k**is less than or equal to the given number using the while loop. - Inside the loop, multiply the value of k with k+1 and divide the result by 2 and convert it into an integer using the int() function.
- Store it in a variable say
**p**. - Print the above result (
**p**) separated by spaces to get the triangular series until the given number. - Increment the value of
**k**by 1 and store it in the same variable**k**. - The Exit of the Program.

**Below is the implementation:**

# Give the number N as user input using the int(input()) function and # store it in a variable. gvn_numb = int(input("Enter some Random Number = ")) # Take a variable say k and initialize its value with 1. k = 1 print("The Triangular series until the given number{", gvn_numb, "} is :") # Loop until the value of k is less than or equal to the given number using the while loop. while(k <= gvn_numb): # Inside the loop, multiply the value of k with k+1 and divide the result by 2 and # convert it into an integer using the int() function. # Store it in a variable say p. p = int((k*(k+1))/2) # Print the above result (p) separated by spaces to get the triangular series until # the given number. print(p, end=" ") # Increment the value of k by 1 and store it in the same variable k. k += 1

**Output:**

Enter some Random Number = 15 The Triangular series until the given number{ 15 } is : 1 3 6 10 15 21 28 36 45 55 66 78 91 105 120

If you wanna write simple python programs as a part of your coding practice refer to numerous Simple Python Program Examples existing and learn the approach used.