What goes through cities and fields, but never moves?

Replace the question mark with the number below given a simple math problem.

A maths symbol is hidden in the below Bar Graph. Can you decipher it?

What does the below image rebus riddle means ?

Can you find the missing number in the third row?
35 20 14
27 12 18
5 2 ?

What are the 50th, 63rd and 100th numbers in the sequence below?
4, 5, 8, 8, 9, 9, 12, 13, 13, 13, 17, 18, ...

How can you take 2 from 5 and leave 4?

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

Can you start the fire using two pieces of wood?

Jack have ten pairs of black socks, eight pairs of white socks and seven pairs of green socks. Everything is mixed in a draw. As there is no light he were not able to identify the colour of the socks. How many of the socks did he want to take to match one pair