9) Emanuele suffers from insomnia. One day at exactly 11:11, he states: "I haven't slept for 53 hours and 53 minutes." At what time did he last wake up?
(A) 5:04
(B) $5: 18$
(C) $5: 58$
(D) 6:04
(E) $6: 18$.
9) The answer is (B)

A period of 53 hours and 53 minutes is equivalent to 2 days, 5 hours, and 53 minutes. Therefore, to calculate when Emanuele woke up, it is enough to subtract 5 hours and 53 minutes from 11:11. The most convenient way to perform this calculation is to subtract 6 hours and then add 7 minutes. This easily yields the required time of 5:18.