10+10 and 11+11 can give you the same answer.

Explain how?

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

I have four wings but can't fly.
I express no emotions.
I am found on the exact spot every time you look.
I keep toiling away with a little sound.

Do you know what am I?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?

Railroad Crossing, look out for the cars. Can you spell that, without any R's ?

A bomb exploded in a room full of married couples and no one died. How?

What has to be broken before you can use it?

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

What is the word or phrase below?
R | E | A | D

You are camping with your friends. You have a flashlight for any emergency and have brought 8 batteries along with you. Your brother calls to tell you that four of those batteries are already dead.

Your flashlight requires two working batteries to run. What is the least number of pairs you will need to test to guarantee that you can get the flashlight on?