How does 많다 turn into 많이?
많다 means many, right? You can conjugate it as 많아요 or 많아 but how does it turn into 많이? I don't see it here: http://dongsa.net/?search=많다 which is why I'm asking. You can find 많니 in the link but I'm guessing it's different from 많이.

Question

Answer

An adjective can be changed into an adverb by adding the adjective stem to "-게", but some of adjectives can take "-이" like "많다", "같다", "높다", "빠르다", etc.

e.g.
많다 => 많(adjective stem) + 게 => 많게
많다 => 많 + 이 => 많이 ("많이" is more commonly used than "많게")
"많다" has two adverbial forms, 
likewise, 높다=>높게/높이, 같다=>같게/같이, 빠르다=>빠르게/빨리

\^o^/

Answer

많니 is for question.  너 친구 많니?=do you have many friends? i 나는 친구가  많이 있어. =i have many friends. 나는 친구가 있어. =i have a friend.

Answer

The word "많-이" is an adverb, and the word "많-게" is the conjugated form with the connective ending "-게" of adjective "많다". So, "많게" is not an adverb. However,  it can be used in the same meaning of adverb "많이".