1 light year = metres.
This is equivalent to miles.
speed of light is typically given as 3.0*10^8 meters per second, or 186,000 miles per second, so by doing the math yourself the answer can be regenerated any time you need it.
so see (186000miles per second)*(60seconds per minute)*(60minutes per hour)*(24hours per day)*(365.25 days per year) gives 5.8697 E +12 miles, very close to the above, but now you know how they got there and need not arbitrarily blindly remember 1 number, and you can PROVE why you believe it.
in the same way: (3.00 times 10 to the 8th power (8 zeros) meters per second)*(3600 seconds per hour)*(24 hours per day)*(365.25 days per year) equals 9.234 e 15 meters similar to answer above but now you know why, and could prove it yourself, or recreate it should you forget it.
if you take that last number and divide it by (1000 meters per kilometer) gives 9.234 e 12 kilometers
this above method is called dimensional analysis where as in above,
(60 second per minute)*(60 minutes per hour)=(3600 seconds per hour)
notice how the dimension minutes cancel each other out leaving seconds per hour... Well wasn't that fun??? In other words... 1.9 trillion miles.