120 tiles
assuming you mean 10" by 10" tiles, 200
Is the room 10 by 6 inches? If so you need 5 12 inch tiles. If it is 10 by 6 feet then the answer is 60.
180
3/10 of a tile
About 195
50
70 tiles. Add an additional 10% for cuts.
36 tiles. First you have to convert 20 inches to feet. There are 12 inches in a foot so 20/12 means you have one and two-thirds length tiles. Then, you have to figure out the lenght of the sides of the room which is the square root of 100 sq ft. which is 10 feet long. Now, you have to figure out how many tiles it will take to do one length of the room by 10/one and two-thirds which is 6 tiles. Finally you have to multiply the length times the width to get how many tiles it takes to fill the room by 6*6=36 tiles
Assuming the tiles are 1 foot squares, you would need 10*15 = 150 tiles.
Your question is confusing because you are using two different scales. If your room is 10 ft x 12 ft and the tiles are 2 ft x 2 ft, the answer is 30 tiles.
It depends on whether the tiles are 18 inch * 18 inch or 18 cm * 18 cm, etc. And also on whether the room is 10ft *10ft or 10 yards*10 yards or 10 metres*10 metres etc.
144/(1.5*1.5) = 64 tiles, but if you are using this to determine how many are needed to tile a room, you need to add at least 10% for edging around the room. So, you probably need at least 71 or more tiles.