Checking something for squareness is easy if you're using a tool called a square -- but only if the object is small. What if it's big? Really big, then what? How do you tell if a child's sandbox is square or if a large picture frame has perfect 90-degree angles at every corner? Instead of fumbling with a small handheld square, check for squareness by using a tape measure. Just measure diagonally from one corner to the opposite one, and note the length; then measure the other diagonal, corner to corner, and compare. Both measurements should be the same. If that is the case, the object is perfectly square. If not, make adjustments until they match up. It works with virtually anything of any size even rectangles. With a simple tape measure, you can be sure anything is perfectly square. Bookcase? Picture-frame glass? No problem. And that's the On The House tip for today.