Till now I am completely unimpressed by Suteguma. He is already at a complete disadvantage because he guessed a 1 in 8 number. He only has 1 guess left. Hopefully it's somehow within his plan, cause otherwise a really, really dumb mistake.
There are only 5 senses..sight,smell,touch,hearing and taste. Since he can't see the only things which make sense are hearing or touch. Hearing can only be done if he has a communication device..or some supernatual ability, which seems very unlikely..so maybe he relies on some sort of clock...