A star is (8.1 ☓ 1023) km away from the earth. Suppose light travels at the speed of (3.0 ☓ 105) per second. How long will it take the light from the star to reach the earth?
Note
Required time = (2.7 ☓ 100,000,000) sec
= (7.5 ☓ 10,000) hrs.