Others

Shortcut for print

print "hello"

$><<"hello" #Better

Think to remove do end block

6.times do |i|
 puts i
end

6.times{|i|puts i} #Better

You can change each to map

(0..9).to_a.each do
 puts "Hello"
end

(0..9).to_a.map do
 puts "Hello"             #Better
end

You can replace your last gets by $_

a=gets
puts a

gets
puts $_

Methods

def a n
n*n
end

a=->n{n*n} # Better

Write n times w

6.times do
 puts "Hello world"
end

puts ["Hello world"] * 6   #Better

# Others