They use decimal points.
The weekend NYT lists a number of economist jokes, including the one above and the ones below.
Why did God create macroeconomists?
To make weather forecasters look good,
Three macroeconomists went hunting and came across a deer. The first shot but missed by a yard left. The second shot and missed by a yard right. The third threw down his rifke and yelled, "We got him."
A priest, a psychologist and an economist go golfing. They end up behind a very slow foursome, that despite their caddies' assistance, is taking an enormous amount of time. They fume and curse until one of their own caddies explains that everyone in the lead group is blind.
The mortified priest then says,"Here I am a man of the cloth and I have been swearing at the slow play of these unfortunate souls." The psychologist chimes in: "I am ashamed of myself; trained to help others and here I have been selfishly critical of these unfortunate men."
The economist ponders the situation and suggests: "Blind golfers should play at night."