It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

Forwards I am heavy, backward I am not. What am I?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

I am sure no one can have two things for dinner. what are they?

If you drop a 15 kg iron bar and a 5 kg bag of cotton from a height of 50 meters which will reach the ground first?

What do the following words have in common?

Assess
Banana
Dresser
Grammar
Potato
Revive
Uneven
Voodoo

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

In case you were starting to feel confident, this one was meant for third graders in Vietnam. The answer is 66, but we don't blame you for scratching your head about how they got there.

Solve the mathematical equation in the picture below.

What does this Rebus Picture means ?