Understanding crystal resonator symbols - which one is 24Mhz?
The decimal point on crystal oscillators or crystal resonators is typically at the millions place or less often the thousands place, in hertz. The number of digits after the decimal point does not affect the frequency. 

Thus, a 24 MHz part would be labeled 24.00 or 24.000, a 2.4 MHz part would be labeled 2.400 or (not seen this yet, but it is possible) 2.40. 

A 32768 Hz crystal would be labeled 32.768 - those are common for RTC applications. 

Other than 32.768 and a few other low frequency crystals used for very specific purposes, it is almost always a megahertz number marked on the part.