Van toc anh sang : 299792458 m / sec
Mot ngay co : 24 X 3600 sec
12 ty nam co : 12 X 1000000000 X 365 X 24 X 3600 sec
=> 12 ty nam anh sang : 12x1000000000x365x24 x3600x299792458 m
hay =12x1000000x365x24x3 600x299792458 km
Last edited by nhocti; 11-02-2011 at 00:24.
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