What is the fastest way to double your money?

During which month do people sleep the least?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

Get total of 120 by using five zeros 0,0,0,0,0 and any one mathematical operator.
Do you ?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

Name the three-letter word that can complete the below words:

A) L O _ _ _ E
B) E D U _ _ _ E
C) _ _ _ E R
D) _ _ _ T L E

If Rajina's daughter is my daughter's mom, who am I to Rajina?

Can you find the ages of a son, father and grandfather based on the following facts?
The sum of the ages of grandfather, father and son is 140 years.
The age of the son in months is the same as the grandfather in years.
The age of the son in days is the same as the father in weeks.

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

What country can make you shiver?