The answer that CPhill calculated, which was: 1.04739 × 10^12 is EXACTLY the same as your answer!!!. Your answer for this: 4/3pi (6.3 * 10^3)^3 =comes from: evalute the product INSIDE the bracket, which comes to:6.3 x 1000 =6,300. Your raise this to the 3rd power: 6,300^3 =250,047,000,000=2.50047 x 10^11. Multiply this last number by 4/3 =333,396,000,000=3.33396 x 10^11. Finally you multiply this last number by Pi. So you get: 3.33396Pi x 10^11. BUT, this is exactly the same as CPhill's answer!!!!!!!!!!!. The reason you don't seem to understand is the fact that you use the word "Pi" in your answer, while CPhill uses the VALUE of Pi, which =3.1415926535........etc. Do you see the where the "problem" is?????