Uh oh! Wolfram|Alpha doesn't run without JavaScript.
Please enable JavaScript. If you don't know how, you can find instructions
here
.
Once you've done that, refresh this page to start using Wolfram|Alpha.
7
0
b
i
l
l
i
o
n
2
c
e
n
t
i
m
e
t
e
r
s
s
p
e
e
d
o
f
l
i
g
h
t
Math Input
Natural Language
Math Input
