Five bells begin to toll together at 12:00 noon and toll respectively at intervals of 4, 5, 6, 7, and 8 seconds. Not including the toll at 12:00 noon, how many more times will all five bells toll together before 2:00 pm (i.e. two hours later)?  Options:
A) 6 B) 7 C) 8 D) 9 E) 10
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.   7200 seconds / 840= 8 + remainder.   The answer is 8.
<result>C</result>
Five bells begin to toll together at 12:00 noon and toll respectively at intervals of 4, 5, 6, 7, and 8 seconds. Not including the toll at 12:00 noon, how many more times will all five bells toll together before 2:00 pm (i.e. two hours later)?