The mathematics are simple. A quality-made man's suit that lasts more than 10 years is a near bargain, compared with one of lesser quality that may hold up for only two or three years. The trick, however, is in spottiing quality, particularly now when suits of all prices are on sale.

"The most expensive part of the garment is not the material, but the labor," says Arthur Adler, chairman and founder of Arthur A. Adler, Inc., quality men's stores in Washington for more than 40 years. And the best workmanship is done by hand.

Here are some things to look for in recognizing a quality suit:

Handmade button holes finished perfectly on the outside [compared to machine buttonholes finished on both sides, and often with rough edges and loose threads].

Soft canvas or hymo lining in front of jacket. Softness apparent in shoulders as well.

Horn or bone buttons, not plastic, attached by hand, rather than stamped on by machine.

Hand-sewn lining, rather than machine-sewn, which is more likely to buckel in drycleaning.

The use of strong fabric in full, not skimpy, pockets.

Patterns that line up on jacket and trousers, rather than lines meeting unevenly on collar, pocket, etc.

Hand-attached felt backing for collar, rather than self-backing.

Adler has several suggestions for the care and treatment of suits to help them last longer. "Never wear the same suit two says running," he says particularly in the summer. Letting a suit "rest" for a day or so gives it a chance to dry out so that it will need less cleaning and last longer. Shaped wooden hangers are better than wire.

Says Adler about quality suits, "They are as sweet as an old pipe and only get better as they get older." CAPTION: Picture 1, Bone button attached by hand, left, and machine-attached plastic button; Picture 2, Good, hand-made button hole, left, and machine-made button hole; Picture 3, Hand-sewn, felt-backed collar, left and machine-sewn self-collar backing; Picture 4, Pocket corner with perfect finish, matched pattern, left, and mismatch with loose thread. Photos by Joe Heiberger -- The Washington Post