#### Answer

The net weight is 330 g.
The weight of one staple is 0.330g or 330mg.

#### Work Step by Step

Subtract the weight of the packaging to find the net weight of the 1000 staples.
$350g-20g=330g$
Divide by the number of envelopes to find the weight per envelope.
$330g\div1000=0.330g$
Move the decimal to convert g to mg.
$0.330g=330 mg$