What number when divided in half becomes zero?

Can you count the number of triangles in the picture below?

What does this rebus means ?

PROG WORKRESS

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

There are five people. One of them shot and killed one of the other five.
We know following clues:
1. Dan ran in the NY City Marathon yesterday with one of the innocent men.
2. Mike consider being a farmer before he moved to the city.
3. Jeff is a top notch computer consultant and wants to install Ben new computer next week.
4. The murderer had his leg amputated last month.
5. Ben met Jack for the first time six months ago.
6. Jack has been in seclusion since the crime.
7. Dan used to drink heavily.
8. Ben and Jeff built their last computers together.
9. The murderer is Jack's brother. They grew up together in Seattle.

Consider yourself to be a famous detective "Sherlock Homles", Can you find the killer?

As a whole I am both
safe and secure.

Behead me and I become
a place of meeting.

Behead me again and I am
the partner of ready.

Restore me, and I become
the domain of beasts.

What am I?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

Can you solve the tricky chess rebus puzzle below by ciphering the hidden meaning?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

If,

A = 1

B = 2

C = 3

...

...

Z = 26.

Based on above rule, you need to find an eleven letter word whose letter sum is equal to 52.