The distance between the brightest star Sirius and earth is 8.7 light years. Calculate the distance in kilometres.

Distance between Earth and Sirius = 8.7 light years
1 light year = 9.46 * 10¹² km 
8.7 light years = 8.7 * 9.46 * 10¹² km
=32,30,20,00,00,00,000 km 
=3.2302 * 10¹⁴ km 

1 light year=9.46*10¹²km there fore 8.7 light year=8.7*9.46*10^{12 km
=82,302,000,000,000}