How does a twelve year old make 400?

A 12 year old can make $400 by doing odd jobs for family friends and neighbors that he knows. Offer to mow lawns, weed gardens, sweep out garages, wash the outsides of Windows, or anything else that people might want done. Make sure you agree on a price before doing the work - if you expect $20 for mowing a large lawn, you don't want to be receiving $5!