Can you count the number of triangles in the picture below?

Can you place six X (crosses) in below board without making three in a row in any way ?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

What number do you get when you multiply all of the numbers on a telephone's number pad?

The product of three consecutive numbers is 7980.
Then the sum of these consecutive numbers would be?

What has no start, end, or centre?

You are playing a game with your friend Jack. There are digits from 1 to 9. You both will take turn erasing one digit and adding it to your score. The first one to score 15 points will win the game.

Would you want to play first or second?

PS: The sum should be exactly 15.

A gardener planted the Lemon trees in a mathematical ordered way (i.e. he planted a tree in rows).
He created a total of 19 rows of trees.

Note: There should be more than 2 trees to count as a row.

What is the minimum number of trees required by the gardener to have 19 rows of trees?

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

If a shopkeeper can only place the weights on one side of the common balance. For example, if he has weights 1 and 3 then he can measure 1, 3 and 4 only. Now the question is how many minimum weights and names of the weights you will need to measure all weights from 1 to 1000? This is a fairly simple problem and very easy to prove also.