What occurs twice in a week, once in a year but never in a day?

If an earthquake is 1 point higher on the Richter Scale than another earthquake which is actually 10 times stronger, how much stronger would an earthquake be if it was just half a point higher on the Richter scale?

If EELS + MARK + BEST + WARY = EASY

What does HELP + BARK + WARD + LEAD equal?

What is the centre of gravity?

A man and a dog were going down the street. The man rode, yet walked. What was the dog’s name?

Find the next number in the sequence

1, 2, 6, 21, 88, __?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

A woman lives in a Tall building thirty-six floors high and served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?