I was wondering if my measurements book that states there are 9,460,000 km in a lightyear is correct. I raise this question because I have recently done some calculations that resulted in my answer being 90,450,800,000,000 km in a LY. How I got this; a light year is how far a light beam travels in a year, and there are 31,536,000 seconds in a year, (1x60x60x24x365). The typical speed light travels at is 300,000,000 m/s. So the obvious calculation to do is 300,000,000 x 31,536,000 ÷ 1,000, which is 9,460,800,000,000. Have I done something wrong in my calculations, or am I right?