irb-loop.rb

irb(main):001:0> # I guess this is as wide as it goes
irb(main):002:0* 80.times do |i|
irb(main):003:1*   print i % 10
irb(main):004:1>   print "\n" if i == 79
irb(main):005:1> end
01234567890123456789012345678901234567890123456789012345678901234567890123456789
=> 80
irb(main):006:0>