Many ~$100 tablesaws have either have terrible dust containment, or none at all. Without any sort of dust containment, these machines will literally coat your shop in sawdust.

Here's how you can contain up to 99% of the sawdust with just a trash bag, and some duct tape

Step 1: Remove the Saw From the Base

Most of those saws that include a metal stand will attach the saw to the stand with 4 bolts; usually one per corner. Remove all four, (set the nuts and bolts into an empty cup so they're not lost) and lift the saw off the stand. Set the saw on a nearby table if you have room, otherwise the floor will do fine (just don't trip on it!).

Step 2: Get a Trash Bag That Will Fit

Next, find a trash bag (industrial drum size works best) that will stretch to all four corners of the stand. Can't find one? Carefully stretch the plastic of a smaller trash bag to fit.

Step 3: Tape the Trash Bag to the Corners

Next, insert the bag into the middle of the stand. See if you can fold the top of the bag over and partially around the stand (not too deep, we want the dust to wind up IN the bag), if you can, disregard step 4. Tape the bag down on each outside corner, going from the inside of the bag to the metal stand.

Step 4: Seal the Edge of the Bag

If you ended up in the same situation that I was in (no bag big enough), you're gonna have to seal around the edge of the bag. Simply stretch the bag to the edges of the metal stand, and tape accordingly. (when taping, align the middle of the tape with the inner edge of the stand and bag).

Step 5: Poke New Bolt Holes

Chances are, you ended up covering up the bolt holes with either bag, tape, or both. Using the largest nail you have on hand (that fits in the original bolt hole), poke through the tape and/or bag. If the nail hole isn't big enough, use a pair of scissors to enlarge it.

Step 6: Reassemble the Saw

Set the saw back on the stand, and use the four original bolts and nuts to cinch it back down to the stand.

Step 7: Tape Around the Base of the Saw

Now, one thing that is quite common on these cheap saws is that the bottom of the base has these weird cast-in handles, and other defects (don't tape over the holes up near the motor, as this is how it gets cool air). Tape around the base of the saw, especially the front and back, to be sure that no dust will escape.