Kilo has to be lower case, so it should be kB for decimal kilobyte. All SI prefixes are case sensitive. Kilo, hecto and deca are weird outliers since they are all written lower case, otherwise SI uses uppercase for prefixes larger than factor one and lower case for those smaller. I know people often don’t pay that much attention to that for bytes since there is nothing smaller than a bit.
There is a huge difference between 5mm and 5Mm. 5Mm = 5000000000mm
Kilo has to be lower case, so it should be kB for decimal kilobyte. All SI prefixes are case sensitive. Kilo, hecto and deca are weird outliers since they are all written lower case, otherwise SI uses uppercase for prefixes larger than factor one and lower case for those smaller. I know people often don’t pay that much attention to that for bytes since there is nothing smaller than a bit.
There is a huge difference between 5mm and 5Mm. 5Mm = 5000000000mm
With other prefixes it gets even more extreme: