Originally Posted by

**sologuitar** (a) How long is 1 light year in miles? Express your answer is scientific notation.

I don't think I can LaTeX this one up, so I'm going for a code block.

This is the unit analysis. I've used the computer format such as "3e8" to represent numbers in scientific notation such as $\displaystyle 3 \times 10^8$.

Code:

3e8 m 3600 s 24 hr 365 d mile
1 year * ----- * ------ * ----- * ----- * ------
s hr d year 1609 m

Years cancel out. So do s, hr, days, and meters. The only unit left is miles.