Ruby - command exit error -

i'm new programming , im having trouble figuring out why im getting error when typing following:

puts "what favorite number?" number = gets.chomp number = number.to_i + 1 puts "i suggest " + number.to_s + " bigger , better number" 

when run in terminal following error appears:

last login: fri jul 10 07:56:21 on ttys000 mba-3093:~ knalavadi$  /var/folders/cv/tm657j1d0kg68fbb1rqtrlgjlg_hrm/t/cleanup\ at\ startup/ruby2-458233138.705.rb.command ; exit;  favorite number? 

the code works. how running script? put in file number.rb , run typing ruby number.rb