Can you find out which number multiplied by itself will give the output as 12345678987654321?

Decode the below four famous ciphers:

8P of the SS
1M of the E
1S of the SS
60M in 1H

John and Jacob are twin brothers. One of them is a liar whereas the other one is a truth-teller.

I called their home number and one of them picked up.
I asked. 'Does John lie?' The person replied with a yes.

Whom did I talk with, John or Jacob?

Katniss and Peeta are liars. They both lie on some specific days.

Katniss lies on Fridays, Saturdays and Sundays. She speaks the truth on all other days.

Peeta lies on Tuesdays, Wednesdays and Thursdays. He speaks the truth on all other days.

Can you tell that one day of the week when both of them will say "Tomorrow, I will lie."?

If,
9 * 8 * 7 = 65
8 * 7 * 6 = 50
7 * 6 * 5 = 37

Find
6 * 5 * 4 = ?

Can you find the missing piece of the Porsche?

John was driving a bus and got stuck when passing through an underpass. Then came Jacob with a needle and got the bus out of the underpass.

What did the boy do?

I can write cow in 13 letters.

Can You?

I am the fastest animal but cannot climb the tree. What am I?

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?