How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

On a certain day, John celebrated his birthday. Two days later, his older twin brother Jacob celebrated his birthday.

Is this even possible? How can it be?

Replace all '*' with digits 1, 2, 3, 4, 5 and 6 to make below statement true.

* *
x *
=====
* * *

A beggar on the street can make one cigarette out of every 6 cigarette butts he finds. After one whole day of searching and checking public ashtrays the beggar finds a total of 72 cigarette butts. How many cigarettes can he make and smoke from the butts he found?

I am a prime number.
The double of myself is equal to the square of me.

which number am I?

John is pretty weird. He likes toffees but hates chocolates. He loves books but never reads. He likes to build his troops in an online game but does not proceed with the war. He likes to go swimming but is afraid of water.

Seeking this behaviour, can you tell whether he likes balloons and parties?

You can see it everyday, But cannot touch it at will. What is it?

I make two people out of one. What am I?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

What have one eye but still cannot see?