Express in scientific notation: 215,000,000    a.2.15x10^8   b.21.5x10^7   c. 215x10^6 d.215x1,000,000  e.0.215x10^9

[latex]2\underbrace{15\ 000\ 000}_{\leftarrow8}=2.15000000\cdot10^8=2.15\cdot10^8\\\\\\Answer:A[/latex] [latex]scientific\ notation:\ a\cdot10^n\ and\ a\in < 1;\ 10);\ n\in\mathbb{Z}\\\\B.\ 21.5\cdot10^7\to21.5 > 10\\\\C.\ 215\cdot10^6\to215 > 10\\\\D.\ 215\cdot1,000,000\to215 > 10\ and\ no\ 10^n\\\\E.\ 0.215\cdot10^9\to0.215 < 1[/latex]