Why is a river so rich ?

It belongs to you, but other people use it more than you do. What is it?

Why is the Hole below a Lock?

The more of this there is, the less you see. What is it?

You are mixing a mixture of cement and Sand with five gallons of water. You have a garden hose giving you all the water you need. The problem is that you only have a four-gallon bucket and a seven-gallon bucket and neither has graduation marks. Find a method to measure five gallons.

What Does this text mean:

important=important

How can you make the following equation true by drawing only one straight line: 5+5+5=550 ?

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?

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?