## Install Racket
Install racket:
```
brew cask install racket
```
Do NOT use *brew install racket*, because it will install the minimal-racket distribution which is missing a lot of tools and packages.
## Write Hello World
```racket
#lang racket
;;
;; From the command line:
;;
;; $ racket -it multiply.rkt
;;
;; Export multiply function so that we can call it from the REPL
;;
(provide multiply)
;;
;; Define the multiply method
;;
(define (multiply number n)
(* number n))
;;
;; Execute function
;;
(multiply 1 2)
(multiply 2 3)
;;
;; Write a unit test for the multiply method
;;
(module+ test
(require rackunit)
(check-equal? (multiply 0 0) 0)
(check-equal? (multiply 2 2) 4))
```