Count the number of lines in the image below ?

Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person's left hand? (For the purposes of this exercise, thumbs count as fingers, for five fingers per hand.) If you cannot estimate the number then try to guess how long the number would be.

Using eight eights and addition only, can you make 1000?

What is full of holes but still holds water?

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

Why 1729 is a magic number? Answer Logically.

Find the 8 in the below-given Image.

Can you convert the number zero(0) into a positive number using just one mathematical operator ?

There is a shop where written:
Buy 1 for $1
10 for $2
100 for $3
I needed 999 and still only paid $3. How could this be financially viable for the shop-keeper?

I know a country, If you remove the last alphabet of its name, it will become a part of your body. Do you name it?