The manager turns on the restaurants to neon signs at the same time of science bank they turned on the same ones on blinks every nine seconds the other side blinks every 15 seconds how many seconds are they back together again
Find the Least Common Multiple (LCM)
First, let's consider the multiple of 9 and 15:
9: 0, 9, 18, 27, 36, 45, 54, 63,
15: 0, 15, 30, 45, 60, 75
The LCM (the smallest number that both 9 and 15 have in common) between 9 and 15 is 45.
So the neon signs will blink together at 45 seconds.
Or more simply:
9 sec lights will blink at:
9 , 18 , 27 , 36 , 45 , 54 , 63 seconds
15 sec ligts will blink at:
15 , 30 , 45 , 60 , 75 seconds
The only common number in these lists is 45.
They will blink together at 45 seconds.