There was some debate about whether the name of our organisation should be written as Angels 5k or Angels 5K. After some research, we plumped for the latter. The reason was that a small ‘k’ is indicative of a metric unit such as a kilogram (kg) or a kilometre as in speed limit of 120k. Strictly speaking the size of a file on your computer should be shown as, say, 50kB but in practice Kb and KB are also widely used.
When it comes to measuring money, a capital ‘K’ is used as in £100K. Since the group’s name came from the original idea that every member would put in £5000 per investment, ‘Angels 5K’ is correct. It’s also appropriate since we invest capital.
By the way, ‘k’ is an abbreviation of ‘kilo’, the Greek word for a thousand.