If it took eight men ten hours to build a wall, how long would it take four men to build it?

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

What is the centre of gravity?

Can you start the fire using two pieces of wood?

81 x 9 = 801. What must you do to make the this equation true?

How can a man go eight days without sleep?

I have branches, but no fruit, trunk or leaves. What am I?

1. How can we put an elephant in the refrigerator?
2. How can we put a Giraffe in a refrigerator?
3. The king of the jungle invites all the animals to a party everyone comes except for one animal, which animal?
4. You come to a crocodile-infested lake, you can't go around it, you can't co under it and you can't go over it, how do you get across?

How many words can a pen with half refill write?

If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?