Hi, I'm Charlie Kasov. I'm a math teacher and today we're going to learn how many kilometers are in a light-second. Now, a light-second is the speed of light per second, and in the metric system, we say that it is two hundred and ninety-nine thousand, or rather, two hundred ninety-nine million, seven hundred and ninety-two thousand, four hundred and fifty-eight meters per second. So, if we want kilometers, we have to multiply by a thousand meters, which means we divide this by a thousand. So, it would be two hundred and ninety-nine thousand, seven hundred and ninety-two point four five eight kilometers per second. Now, if we wanted to figure out a light year from this, we would just multiply the seconds. So, it would be this times sixty would give us a minute, and then times sixty again would give us an hour, times twenty-four would give us a day, and times three hundred sixty-five point two five would give us a light year, which would be nine point four six 0 five two eight four times ten to the twelfth kilometers. So, that is a light year. But going back, there are two hundred ninety-nine thousand, seven hundred and ninety-two point four five eight kilometers per second in a light second. So, I'm Charlie Kasov. Thanks a lot.