# R Program to Make a Simple Calculator

In this example, you will learn to create a simple calculator that can add, subtract, multiply and divide two numbers entered by the user.

To understand this example, you should have the knowledge of following R programming topics:

## Example: Simple Calculator in R

```
# Program make a simple calculator that can add, subtract, multiply and divide using functions
add <- function(x, y) {
return(x + y)
}
subtract <- function(x, y) {
return(x - y)
}
multiply <- function(x, y) {
return(x * y)
}
divide <- function(x, y) {
return(x / y)
}
# take input from the user
print("Select operation.")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
choice = as.integer(readline(prompt="Enter choice[1/2/3/4]: "))
num1 = as.integer(readline(prompt="Enter first number: "))
num2 = as.integer(readline(prompt="Enter second number: "))
operator <- switch(choice,"+","-","*","/")
result <- switch(choice, add(num1, num2), subtract(num1, num2), multiply(num1, num2), divide(num1, num2))
print(paste(num1, operator, num2, "=", result))
```

**Output**

[1] "Select operation." [1] "1.Add" [1] "2.Subtract" [1] "3.Multiply" [1] "4.Divide" Enter choice[1/2/3/4]: 4 Enter first number: 20 Enter second number: 4 [1] "20 / 4 = 5"

In this program, we ask the user to choose the desired operation. Options 1, 2, 3 and 4 are valid.

Two numbers are taken from the user and a `switch`

branching is used to execute a particular function.

User-defined functions `add()`

, `subtract()`

, `multiply()`

and `divide()`

evaluate respective operations.