Your job is to measure 45 minutes if you have only two cords and matches to light the cords.
1. The two cords are twisted from various materials, so their different segments can burn at different rates.
2. Each cord burns from end to end in exactly one hour.
When you stop to look, you can always see me. But if you try to touch me, you can never feel me. Although you walk towards me, I remain the same distance from you. What am I?
A four-digit number (not beginning with 0) can be represented by ABCD. There is one number such that ABCD=A^B*C^D, where A^B means A raised to the B power. Can you find it?
The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.
What can a student say to prevent his being expelled from school?
