The square root of number 121 is "11". What is the square root of the number "12345678987654321."?

Decode below rebus
D
N
A
T
S , D

An exterior architect is asked by a builder to plant seven trees in a manner that there are exactly six rows of trees in a straight line and each row has three trees in particular.

How will he do it?

What does man love more than life, and hate more than death or mortal strife; that which satisfied men want; the poor have, and the rich require; the miser spends, the spendthrift saves, and all men carry to their graves?

If we add four times the age of John four years from now to five times his age five years from now we get ten times his current age.

How old will John be two years from now?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

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?

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.

It belongs to you, but other people use it more than you do. What is it?