O_er_t_o_

Complete the missing letters of the given word.

If,

20 % 5 = 24

21 % 7 = 33

42 % 6 = 67

Then;

66 % 6 = ?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

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

A mules travels the same distance daily.
I noticed that two of his legs travels 10km and the remaining two travels 12km.
Obviously two mules legs cannot be a 2km ahead of the other 2.

The mules is perfectly normal. So how come this be true ?

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

Speaking of rivers, a man calls his dog from the opposite side of the river. The dog crosses the river without getting wet, and without using a bridge or boat. How?

Remove two matchsticks to make the below equation correct.

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211