Course

Additional

Find the Statistical Mode Write to a File Format Decimal Places

Data Frames

Convert a List to a Dataframe Create an Empty Dataframe Combine Two Dataframe into One Change Column Name of a Dataframe Extract Columns From a Dataframe Drop Columns in a Dataframe Reorder Columns in a Dataframe Split Dataframe Merge Multiple Dataframes Delete Rows From Dataframe Make a List of Dataframes

Introduction

"Hello World" Program Add Two Vectors Find Sum, Mean and Product of Vector in R Programming Take Input From User Generate Random Number from Standard Distributions Sample from a Population Find Minimum and Maximum Sort a Vector

Strings

Concatenate Two Strings Find the Length of a String Check if Characters are Present in a String Extract n Characters From a String Replace Characters in a String Compare two Strings Convert Factors to Characters Trim Leading and Trailing Whitespaces

Vectors

Concatenate a Vector of Strings Check if a Vector Contains the Given Element Count the Number of Elements in a Vector Find Index of an Element in a Vector Access Values in a Vector Add Leading Zeros to Vector

Decision and Loops

Find the Factorial of a Number R Multiplication Table Check Prime Number check Armstrong Number Print the Fibonacci Sequence Check for Leap Year Check if a Number is Odd or Even in R Programming Check if a Number is Positive, Negative or Zero Find the Sum of Natural Numbers

Functions

Convert Decimal into Binary using Recursion in R Find the Factorial of a Number Using Recursion Find the Factors of a Number Fibonacci Sequence Using Recursion in R Find H.C.F. or G.C.D.Find L.C.M.Make a Simple Calculator Sum of Natural Numbers Using Recursion

R Program to Find the Sum of Natural Numbers

Example 1: Find sum of natural numbers without formula


              
# take input from the user
num = as.integer(readline(prompt = "Enter a number: "))

if(num < 0) {
    print("Enter a positive number")
} else {
    sum = 0

    # use while loop to iterate until zero
    while(num > 0) {
        sum = sum + num
        num = num - 1
    }

    print(paste("The sum is", sum))
}

Output


              
Enter a number: 10
[1] "The sum is 55"

Here, we ask the user for a number and display the sum of natural numbers upto that number.

We use while loop to iterate until the number becomes zero. On each iteration, we add the number num to sum, which gives the total sum in the end.

We could have solved the above problem without using any loops using a formula.

From mathematics, we know that sum of natural numbers is given by


              
n*(n+1)/2

For example, if n = 10, the sum would be (10*11)/2 = 55.

Example 2: Find sum of natural numbers using a formula


              
# take input from the user
num = as.integer(readline(prompt = "Enter a number: "))

if(num < 0) {
    print("Enter a positive number")
} else {
    sum = (num * (num + 1)) / 2;

    print(paste("The sum is", sum))
}

Output


              
Enter a number: 10
[1] "The sum is 55"