[tex]1km=1,000m\to1m=0.001km\\\\1h=3,600s\to1s=\dfrac{1}{3,600}h\\\\2.998\cdot10^8\ \frac{m}{s}=2.998\cdot10^8\cdot\dfrac{0.001}{\frac{1}{3600}}\ \frac{km}{h}\\\\=2.998\cdot100,000,000\cdot0.001\cdot3600\ \frac{km}{h}\\\\=2.998\cdot100,000\cdot36\cdot100\ \frac{km}{h}\\\\=2.998\cdot36\cdot10^7\ \frac{km}{h}=107.928\cdot10^7\ \frac{km}{h}\\\\=\boxed{1.07928\cdot10^9\ \frac{km}{h}}[/tex]
