Please convert 8240 lb to kg.

There are 453.59 grams/lb.

There are 1000 g/kg.

Watch the unit we don't want to keep cancel and the unit we want is left.
8240 lb x (453.59 g/lb) x (1 kg/1000 g) = ??
or you can use an on-line calculator.
http://www.convertunits.com/from/lbs/to/kg