What four weights can be used to balance from 1 to 30 pounds?

This is a classy optical illusion puzzle. What more you can find except bricks in the image below?

Can you count the number of triangles inside a triangle?

There are a hundred statements.

First person says: At least one of the statements is false.

Second person says: At least two of the statements is false.

Third person says: At least three of the statements are false.

Fourth person says: At least four of the statements are false.

..

..

..

Hundredth person says: At least a hundred of the statements are false.

Analysing it, how many statements do you think are false and how many are true?

Below toothpicks/matchsticks indicate the group of fishes moving from west to east direction. Can you make them move from east to west by just moving three toothpicks/matchsticks?

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

Arrange the numbers 1, 2, 3, 4, 5, 6, 7, 8 and 9 above and below the division line in a manner that the thus formed fractions equal to 1/3.

(You can use one number only once)

Can you find out the next digit in the following series ?

0, 0, 1, 3, 2, 6, 3, 9, 4, 12, 5, ?

A blonde put eyeliner on her head. Why?

You see me once in June, twice in November, and not at all in May. What am I?