Answer:
36 tiles
Step-by-step explanation:
Because the room is square, the numbers of tiles along the edge of the room were multiplied by the same number, meaning that:
81 = x²
So to find x, we must square root both sides of the equation:
x = 9
So the length of one side is 9 tiles. Now to calculate the circumference, as each side of a square is the same length, we can multiply this number by 4:
9 * 4 = 36
So there are 36 tiles along the edge of the room.
Hope this helps!