Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and 12 seconds respectively. In 30 minutes, how many times do they toll together ?
Choose one
A) 22
B) 72
C) 37
D) 16
E) 88
Explanation:   L.C.M. of 2, 4, 6, 8, 10, 12 is 120.   So, the bells will toll together after every 120 seconds(2 minutes).   In 30 minutes,they will together  (30/2)+1= 
<gadget id="calculator"> (30/2)+1</gadget>
<output>16</output>
16 times   Answer: 16) 16
<result>D</result>
Six bells commence tolling together and toll at intervals of 2, 4, 6, 8 10 and 12 seconds respectively. In 30 minutes, how many times do they toll together ?