How can you leave a room with two legs and return with six legs?

Name a key which is hardest to turn.

John gave half of the apples he had plus one more to Jacob. He gave half of the remaining ones plus one more to James. Now, John was left with just one apple.

Can you find out how many did he have in the beginning?

The answer I give is yes, but what I mean is no. What was the question?

What has 13 hearts but no other organs?

Below, you can see some coding:
January = 1017
February = 628
March = 1335
April = 145
May = 1353
June = 1064
July = 1074
August = 186

Now deciphering the way it has been coded, can you find out how September will be coded?

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

You see me once in June, twice in November, and not at all in May. What am I?

The more you take me, the more you leave me behind.
Who Am I?

All of you like to eat me. I am a five-lettered word. Remove the first two and I turn into an infamous animal. Remove just the first and I become a heinous crime. Remove the first and the last and you can groove on me.

Can you guess who am I?