It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

Find the next number in the sequence

5 12 24 36 ?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?

These types of puzzles are known as charades. What you have to do is to find two words that are referred to in the first stanza and the second stanza and put them together to form the third word in the third stanza.

Just for example, if my first refers to 'off' and my second refers to 'ice', then my whole will be the 'office'.

My first is present - future's past -
A time in which your lot is cast.

My second is my first of space
Defining people's present place.

My whole describes a lack of site -
A place without length, breadth, or height.

There are three boxes of different sizes with three cupcakes inside each of the boxes in Christina's kitchen. At night her daughter wakes up and goes to the kitchen. She opens a box and eats all three cakes.

But in the morning Christina finds out that each box still had three cupcakes. How?

Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

In the addition below, all digits have been replaced by letters. Equal letters represent equal digits and different letters represent different digits.
ABCABA
BBDCAA
ABEABB
ABDBAA
------- +
AAFGBDH
What does the complete addition look like in digits?

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat