A megahertz is one million (or 106) hertz.
See hertz, kilohertz (one thousand hertz), gigahertz[?] (109 hertz), terahertz[?] (1012 hertz), and petahertz[?] (1015 hertz).
... (W) 162 Democratic-Republican George Clinton (162) Charles C. Pinckney[?] 14 Federalist Rufus King (14) Other elections: 1792, 1796, 1800, 1804, 1808, 1812, ...