First, find the area for the kitchen floor: 16.5*15=247.5 squared feet
Then find the area for one tile: 0.5*0.5=0.25 squared feet
Finally, divide the mayor area between the minor: 247.5/0.25= 990 tiles.
Also you can do it in this another way:
First, divide length of the kitchen floor between the length of one tile: 16.5/0.5=33
Then, do the same for the height: 15/0.5=30
Finally multyply both results: 33*30= 990 tiles.
