## Exercise 01

1+1
3 * 7
4 ^ 4
3 + 5 ^ 2
(3 + 5) ^ 2
pi
pi * 5 ^ 2

## Challenge #1. Write an expression that returns the area of a circle whose diameter is 20.

## HINT: area = pi times radius squared

pi * (20 / 2) ^ 2

## Challenge #2: Compute the square root of 1,000

sqrt(1000)

## Saving your work as variables

x = 2 * 7
x

y = 3 + 4

x + y
x + y ^ 4

## Recover from an incomplete command
z = 5 +
6

## Reassigning variables
z = 5
z
z = 55
z
z = z ^ 3
z

## Comparison (logical) operators
x
x > 5
x < 14
x <= 14
x > y
x >= y * 2
x == 14
x == y * 2

## Better names for objects & object classes

show_size = 9
class(shoe_size)

shoe_color = 'brown'
class(shoe_color)

## What happens if you add apples and oranges?

shoe_size + shoe_color

## Did I mention that R is case-sensitive?

shoe_color == 'brown'
shoe_color == 'Brown'

## Comparing Text

"HELLO" == "hello"
"HELLO" == toupper("hello")

## Plotting commands (teaser)

hist(rnorm(1000))