Question

The "Open" sign at Cenzo's flashes every 4 seconds. The "Open" sign at The Kettle flashes every 5 seconds and the "Welcome" sign at Centrella's Deli flashes every 6 seconds. If the signs are turned on and flash at the same time, how long will it take for them to flash at the same time again?

Answer 1

It will take 60 ( one minute) for the signs to flash at the same time


Find the lcm ( least common denominator)
4: 4,8,12,16,20,24,28,32,36,40,44,48,52,
56,60
5: 5,10,15,20,25,30,35,40,45,50,55,60
6: 6,12,18,24,30,36,42,48,54,60