What does the below rebus riddle means?

Too much grey makes things difficult. However, your task here is to find the elephant hidden in the picture.

With the help clues provided in the image, can you find the 5 digit key?

John is the son of Jacob.
So,
Jacob is the_____of John's father?

Replace the alphabet with the number such that the below equation holds.

HAPPY
+ DIWALI
--------------
HDLALA
--------------

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

O_er_t_o_

Complete the missing letters of the given word.

John was a very careless driver, so his owner Jacob gave him an offer that he will get an incentive of Rs.30 for every bottle box he delivered without breaking it and he will be charged Rs.90 for every bottle box he broke. Jacob gave John 100 bottles-box to deliver. After delivery, Jacob paid John Rs.2400. How many bottles-box did John break?

What number do you get when you multiply all of the numbers on a telephone's number pad?

Queen Elizabeth organised a royal party.

To Avoid uninvited guest royal family set a password.
Jack (an uninvited person) plan to enter the party. He stand nearby the door.

First guest comes, the security person said 'twelve' and guest replied with six.
Second guest comes , the security person said 'six' and guest replied with 'three'.

Jack thought is enough and he walked to the entry point. The security person said 'eight' , Jack replied smilingly 'four'.
He was immediately thrown out of the party. why ?