A subject as important as numbers in machine shorthand deserves to be revisited. Steno students and some professionals, I'm sure, struggle with how they should do their numbers and get them to come out correctly in the transcript or realtime. The two major schools of thought, I believe, are using the number bar and writing your numbers out in words.
The number bar is a quick, efficient way of inputting numbers. Despite this, I think for some people it might be a cause for pause when they struggle to convert the spoken word "six" to the numerical figure "6." In my opinion, a number bar -F combination is pretty much an arbitrary brief to mean the number 6, as far as theory goes and "writing by sound," a phrase which my dear teachers have shoved down my throat these past few years. Because of this, consistent drilling and practice are necessary to be accurate and fast with numbers.
Using the number bar also allows you to invert your numbers by adding an "EU" or an * to the stroke, as steno student blogger Simville02 reminded me recently. "For example, 43 = 34I, 92 = 2I9, 60 = 0I6..." You can also double them up, so "To write numbers such as 22, 55, and 88, you use E (2E, 5E, E8)."
Writing numbers out as words as spoken is the other major method of getting 'em down. The biggest reason people cite for writing their numbers out is accuracy. Lord knows sometimes the fingers hit the wrong keys, and with the number bar, there's no context and really no way to verify if what you have in your notes is what was actually said. With written numbers, a misstroke isn't as big a deal, and the reporter can usually figure out what they meant to write.
The spoken word "fifty-eight" is written as TPEUFT/AEUGT or some variation thereof, and a CAT software dictionary entry is made for that combo to come out as 58. Some people will even go a step further and cut it down to one stroke, TPAEUGT. This second method can result in conflicts, however, but as long as you can work around them and commit a few exceptions to memory, this might be a more a "organic" way of writing as our brains are trained to respond to the sounds of the words.
Within your CAT software itself, there are probably number conversion settings that are available to help you get a cleaner translation. The picture below is from the number settings tab in Total Eclipse, but check out the help file that goes along with your software to get details on how to tweak your specific settings.
So the last winter break of my court reporting education, I actually created an entire Eclipse dictionary for numbers that were written out, including the extremely shortened ones. During my attempt to convert over to this new system, there was too much hesitation as my brain was confused as to where to send my fingers, so right now I'm working on perfecting the number bar system. To infinity and beyond, court reporters, CART providers, and captioners!