事半功倍

A thing or matter; an event or incident; work or business; to serve; to do or perform.

Half; semi-; incomplete; in the middle; a very small amount; part of something; and a half (after a number).

Achievement or accomplishment; merit or good result; work or effort; success; a type of mourning attire.

Multiplier, times, fold; to increase or multiply; to add to the original amount; to increase further; archaic: to go against, to betray; archaic: to turn one's back on.