Six lights begin to flash together at 12:00 noon and flash respectively at intervals of 3, 4, 5, 6, 7, and 8 seconds. Not including the flash at 12:00 noon, how many more times will all six lights flash together before 1:00 pm (i.e. one hour later)?  Choose the correct answer.
A) 4	B) 6	C) 8	D) 10	E) 12
The least common multiple is 2*2*2*3*5*7= 
<gadget id="calculator">2*2*2*3*5*7</gadget>
<output>840</output>
840.   3600 seconds / 840= 4 + remainder.   The answer is 4.
<result>A</result>
Six lights begin to flash together at 12:00 noon and flash respectively at intervals of 3, 4, 5, 6, 7, and 8 seconds. Not including the flash at 12:00 noon, how many more times will all six lights flash together before 1:00 pm (i.e. one hour later)?