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

You are provided with a grid (as shown in the picture). Can you fill the squares with numbers 1-8 in a manner that none of the two consecutive numbers are placed next to each other in any direction (vertically, horizontally or diagonally?)

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

I have an eye but still cannot see.

Who am I?

What's the only room from which no one can enter or leave

By moving exactly three matchsticks can you make the below equation true.It can be solved by 3 ways.

Which word does the below Plexor means ?

What's a single-digit number with no value?

I guess 76.8% of readers will like this riddle.

What's the least number of people should read this post?

A river should be crossed by a father, a mother and their two sons and two daughters.
There are some rules that should be followed while crossing the river. There can be only two people in the raft while crossing. The daughters cannot be with their father unless there is the presence of the mother. The sons cannot be with their mothers unless the father is present. Unless the guard is on the board, the criminals cannot be with any of the family members. Only the adults like the father, the guard, and the mother knows to use the raft.

How will they cross the river?