puts 0.zero? # => true (is this number zero?)
puts 1.0.zero? # => false
puts 0.0.nonzero? # => nil (works like false)
puts 1.nonzero? # => 1 (works like true)
puts 1.integer? # => true
puts 1.0.integer? # => false
puts 1.scalar? # => false: not a complex number. Ruby 1.9.
puts 1.0.scalar? # => false: not a complex number. Ruby 1.9.