How many triangles are there on the puzzle below?

There is a shop where written:
Buy 1 for $1
10 for $2
100 for $3
I needed 999 and still only paid $3. How could this be financially viable for the shop-keeper?

Find the missing number in the sequence below:

The following alphametic has only one solution. Can you find it?
ENLIST + SILENT + LISTEN = ANAGRAM

PS: You may start the number from 0.

A man dies of old age on his 25 birthday. How is this possible?

Can you find the largest Three-digit number whose sum is 14 and whose square is less than 5,00,000?

If you paint a brown house white it will become a white house. If the stoplight changes from red to green, then the light is green. So, if you throw a white shirt into the Red Sea, what will it become?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?