If 1+9+8=1, what is 2+8+9?

When is the top of a mountain similar to a savings account?

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?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

Why are all black people so quick ?

I inserted a coin in a bottle and closed its mouth with the help of a cork. Now, I was able to take the coin out from the bottle without taking out the cork or breaking the bottle. Can you tell me how I did it?

What 4-letter word can be written forward, backward or upside down, and can still be read from left to right?

The person who makes it has no need for it; the person who buys it has no use for it. The person who uses it can neither see nor feel it. What is it?

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

Next Number in the Series,

5, 16, 49, 104, ?