51.times do |i|
  if i.even?
    puts "i=#{i}, even, #{i.even?}"
  else
    puts "i=#{i}, odd, #{i.even?}"
  end
end

51.times do |i|
  puts "i=#{i}, even, #{i.even?}" if i.even?
  puts "i=#{i}, odd, #{i.even?}" unless i.even?
end

51.times do |i|
  puts "i=#{i}, even, #{i.even?}" if i.even?
  puts "i=#{i}, odd, #{i.even?}" if i.odd?
end

51.times { |i| i.even? ? puts("i=#{i}, even, #{i.even?}") : puts("i=#{i}, odd, #{i.even?}") }

51.times do |i|
  i.even? ? puts("i=#{i}, even, #{i.even?}") : puts("i=#{i}, odd, #{i.even?}")
end