In the Windows Operating system, The R installer will have created an icon for R on the desktop and a Start Menu item. Double-click the *R* icon to start the R Program; R will open the console, to type R commands.

The greater than sing (>) in the console is the prompt symbol. In this tutorial, we will use the R language as a calculator (we will be Using R as a Calculator for mathematical expressions), by typing some simple mathematical expressions at the prompt (>). Anything that can be computed on a pocket calculator can also be computed at the R prompt. After entering the expression on the prompt, you have to press the Enter key from the keyboard to execute the command.

### Using R Language As a Calculator

Some examples using R as a calculator are as follows

> 1 + 2 #add two or more numbers > 1 - 2 #Substracts two or more numbers > 1 * 2 #multiply two or more numbers > 1 / 2 #divides two more more numbers > 1 %/% 2 #gives the integer part of the quotient > 2 ^ 1 #gives exponentiation > 31 %% 7 #gives the remainder after division

These operators also work fine for complex numbers.

Upon pressing the enter key, the result of the expression will appear, prefixed by a number in a square bracket:

> 1 + 2 [1] 54

The [1] indicates that this is the first result from the command.

One can also use R as an advanced scientific calculator. Some advanced calculations that are available in scientific calculators can also be easily done in *R* for example,

> sqrt(5) #Square Root of a number > log(10) #Natural log of a number > sin(45) #Trignometric function (sin function) > pi #pi value 3.141593 > exp(2) #Antilog, e raised to a power > log10(5) #Log of a number base 10 > factorial(5) #Factorial of a number e.g 5! > abs(1/-2) #Absolute values of a number > 2*pi/360 #Number of radian in one Babylonian degree of a circle

Remember R prints all very large or very small numbers in scientific notation.

### Order of Precedence/ Operations

The R language also makes use of parentheses for grouping operations to follow the rules for the order of operations. for example

> 1 - 2/3 #It first computes 2/3 and then subtracts it from 1 > (1-2)/3 #It first computes (1-2) and then divides it by 3

The R Language recognizes certain goofs, like trying to divide by zero, missing values in data, etc.

> 1/0 #Undefined, R tells it an infinity (Inf) > 0/0 #Not a number (NaN) > "one"/2 #Strings or characters is divided by a number

**Further Reading:** Computing Descriptive Statistics in R

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