No, they are different things. This would be like calculating an apple into an orange.
wire two 8 ohm speakers in a parallel circuit!
volts, amperes, ohms, hertz, watts
16 Ohms. Yes 16 ohms in series. 4 ohms in parallel
The nominal 8 inch speaker impedance can be 4 ohms, 8 ohms or 16 ohms. It depends on the make of the loudspeaker not on the 8 inches.
Positive
Mega is 8 X 10^6 and Kilo is 8000 X 10^3. For every 3 you go down in powers you divide by 1000, so 8 Mega ohms is 8,000,000 ohms. 8,000 Kilo ohms or 0.008 Giga ohms.
Use 5.2 ohms, which is the closest to 8 ohms.
For an 8 ohm speaker, 8 ohms is perfect. "Good" and "bad" are relative to the application.
Jan Hertz was born on July 8, 1949, in Denmark.
Though it is tempting to say the difference is 2 ohms (8 ohms minus 2 ohms equals 6 ohms), lets look at some things. The 6 ohms is 3/4ths the resistance of the 8 ohms. If the resistances are loads, the 6 ohm load will draw 1/3rd more current than the 8 ohm load. The 8 ohm load will draw 3/4ths as much as the 6 ohm load. Those are some differences between 6 ohms and 8 ohms.
There is no amplifier with an output impedance of 8 ohms or 4 ohms on the market. All audio amplifiers really have an output impedance of less than 0.1 ohms. Scroll down to related links and look at "Amplifiers, loudspeakers and ohms"