D.) 9,987,000 becomes 9.987 x 10^6
As there are 81 tiles total, that makes your area 81. Being a square, that makes your area equation A=s^2. As you need a side, this makes your equation s=√A. Plugging in 81 as A, we get s=√81=9, so an edge has 9 tiles.
0.12 can be written as 12/100 or 3/25. It is very much a rational number as no square root is involved in the fractional form of the number.
1. 90°
2. 5.74
3. 90°
4. 7
:))