I've been asked to fix a bike after a bit of a drunken off by the owner.
I think cheapness is the key!

The chain was broken and one of the little "washers" that space the links-over the pins-has gone awol(is that a suitable description?!)

I'm guessing it was the right length and rideable before. Would it make much difference to the rideabilty or usabilty if i just removed a link?
Or should i go buy a new one!

FS or HT?
if HT, run the chain around the biggest sprocket at the back, and the biggest at the front, ignoring the deraileur for now. hold the chain together at the ends, then add two coplete links ( so an inner and an outer make 1 complete one ). this is rule of thumb for the ideal length of chain. if you're one complete one shy after you've taken the 'missing bits' out, it'll likely be fine. thread it through the mech and join it. then gently and carefully try it, big to big. if the mech doesn't disintegrate, or point directly at the front hub, you'll be alright.

Its a Mongoose Tyax Hardtail.

Thanks i'll give that a check,see how long it actually is.
Make sure there's not more missing than i thought!