Why do we preferably have round manhole covers and not square ones?

What numbers should go on the bottom line?
3 6 9 15
8 2 10 12
11 8 19 27
19 10 29 39
? ? ? ?

You measure my life in hours
I serve you by expiring
I vanish faster when I am thin
and slower when I am thick
The wind is my energy
What am I?

There are two beautiful yet remote islands in the South Pacific. The Islanders born on one island always tell the truth, and the Islanders from the other island always lie.
You are on one of the islands and meet three Islanders. You ask the first which island they are from in the most appropriate Polynesian tongue, and he indicates that the other two Islanders are from the same island. You ask the second Islander the same question, and he also indicates that the other two Islanders are from the same island.
Can you guess what the third Islander will answer to the same question?

A prisoner is told: "If you tell a lie, we will hang you and if you tell the truth, we will shoot you." What did the prisoner say to save himself?

Find the next number in the series.
1 10 24 43 67 ?

Today, I celebrated my 32nd birthday but I was born in 1972.
How is this possible?

Why do Chinese men eat more rice than Japanese men do ?

If you drop me I’m sure to crack, but give me a smile and I’ll always smile back. What am I?

Rectify the following equality 101 - 102 = 1 by moving just one digit.