1. I read on my physics book that "zeros located at the end of a number are not significant if they are not followed by a decimal point." it also gave an example: 3000 K, in this case, there is only 1 significant figure. However, the number 93,000,000 m, on my book it says only the first five digits are significant. But i think there are only 2 significant figures according to the previous definition? I was confused. 2. What does 'size' mean in Physics? means the surface area? 3. The time it takes to play a CD in your stereo. My teacher said the answer was 3.6 kilosecond. but i didn't get it. Thanks a lot.