what does the below math rebus puzzle mean?

How many sides does a circle have?

What is greater than gold but cannot be bought. it can never be sold and can earn if its sought. though it can be broken, it can still be fixed. for by birth it can't start nor by death it is ended.what am i?

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

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Readers with excellent focus can find three differences between the camping scene pictures in 16 seconds. Can you? Test your eye power now!

John is now two fifth of his older brother's age and two years from now he will be half of his older brother's age.
Two years ago, John was only one-fourth the age of his older brother age at that time.

How old is John now?

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?

A man is found dead with a knife in his back When the investigation is done. A chair lays beside him and the forensic team finds moisture around the body.

If he committed suicide, how did he do it?