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

If nine thousand, nine hundred nine dollars is written as $9,909,
how should twelve thousand, twelve hundred twelve dollars be written?

When 99 is considered higher than 100?

Two girls were born to the same mother, on the same day, at the same time, in the same month and year and yet they're not twins. How can this be ?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

Today, I celebrated my 32nd birthday but I was born in 1972.
How is this possible?

By using all numbers, i.e. 123456789 and subtraction/addition, operators number 100 can be formed in many ways.
Example: 98 + 7 + 6 - 5 - 4 - 3 + 2 - 1 = 100

But if we add a condition use of the number 32 is a must. Then there are limited solutions.
One of such solution is: 9 - 8 + 76 + 54 - 32 + 1 = 100

Can you tell me any other solution?

Two friends were betting. One said to the other, "The coin will be flipped twenty times and each time the coin lands on the head, I will give you $2 and each time it lands on the tale, you will give me $3." After flipping the coin twenty times not a single penny was exchanged among them.

How many times did the coin land on heads?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

It has a long neck, A name of a bird, Feeds on cargo of ships, It's not alive,

What is it?