A.how many 12 inch square tiles would be necessary to cover the floor of a
square room that measures 14 feet on a side?

A 12 inch square tile is 1 foot on a side so here is the picture of one
12 inch square tile:

          

Here is the picture of the square room 14 feet on a side.

          

Count them and you'll find there are 196 of them.

But an easier way to get 196 is to multiply 14 by 14.

Edwin