0.00431, approx.
Is this really a serious question? Holy cow...
128.2 tiles
You are looking for the square root of 225 which is 15. (15x15=225)
52 tiles (with a bit left over !)
15x15= 225
Think about it for yourself
225
225 squares.
15w5e73273527e
15x15
225
15x15
15. 15x15=225
15x15=225
It is not a property. It is the binary operation called multiplication.
225 square inches (15x15)