13 ... read it right to left and you'll be accurate.irb(main):096:0> s = 'FINISHED FILES ARE THE RE-
irb(main):097:0'
irb(main):098:0' SULT OF YEARS OF SCIENTIF-
irb(main):099:0'
irb(main):100:0' IC STUDY COMBINED WITH THE
irb(main):101:0'
irb(main):102:0' EXPERIENCE OF YEARS.'
=> "FINISHED FILES ARE THE RE-\n\nSULT OF YEARS OF SCIENTIF-\n\nIC STUDY COMBINED WITH THE\n\nEXPERIENCE OF YEARS."
irb(main):103:0> s.scan('F').size
=> 6
That's an example of the same skill that allows you to read the scrambled text working against, rather than for, you. It's also an example of how even good spellers can be less than perfect proofreaders.
13 ... read it right to left and you'll be accurate.