How can you make number one disappear by adding something to it?

Find the last number in the series below:

voN luJ yaM raM ---

Why do you find that most of the buildings are deprived of the 13th floor?

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?

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

All of Jacob's shoes are red except two.
All of Jacob's shoes are green except two.
All of Jacob's shoes are yellow except two.

How many shoes does Jacob have?

Can you move 2 matchsticks to form four equal sized squares.

Its something that each of us devours,
Not just us but birds, beats, trees, and flowers,
Frets iron and nibbles steel,
Toil hard stones to meal,
Exterminates king, collapse town,
And blows the mountains down.

1 dollar = 100 cent
= 10 cent x 10 cent
= 1/10 dollar x 1/10 dollar
= 1/100 dollar
= 1 cent

=> 1 dollar = 1 cent

solve this tricky problem?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?