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

Luis Garavito killed Density x Volume.

Who is Luis Garavito ?

How many triangles are there in the picture below?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

Two prisoners Jack and Jill are locked in a cell.
There is open window approx 40 feet above the ground of the cell.
They are never able to reach there.

Then they plan to escape by a tunnel and they start digging out.
After digging for more than 20 days, Jill comes with the different plan and they escaped.

what was the plan ?

What does the following represent?

N N N N N N N

A A A A A A A

C C C C C C C

No matter how little or how much you use me, you change me every month. What am I?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

Which famous Hollywood movie name is hidden in the below rebus?