Question

A light flashes at an interval of 9 minutes. If it was swtiched on at 11 O' clock, will it flash at 11:45 ?

Answer 1

To find when the light will flash, we need to repeatedly add 9

The first light comes at 11:00 , the next one will be 11:00 + 9 minutes = 11:09 ,
Next one will be after 9 minutes again , which is 9 + 9 = after 18 minutes - This is nothing but the table of 9

So, the light will flash after 9 min, 18min , 27min , 36 min, 45 min , 54 min

11:45 will be after 45 min from 11 O'clock.

So, the light will flash at 11:45.