However many 9's one adds onto 99.999% confident, it's never 100%.

I thought that 99.999999.... actually does equal 100, no?

There is no instantiation of "however many" with an integer, n, that results in the "equals 100%" result (because then n+1 would result in more that 100% which is just way off). There are some more precise things we can say along the lines of "limit as n approaches infinity where..." that express what is going on fairly clearly.

Writing the "99.9 repeating" syntax with the dot does mean "100" according to how the "writing the dot on the numbers" syntax tends to be defined, which is I think what you are getting at but seems different to what Berry seems to be saying.