The E6B is fine for the US and for PPL level over here, it does most but certainly not all of the ATPL.
If you are doing ATPL exams in UK/EASA then you should really INVEST in a CRP-5 or equivalent. Buying any other is a false economy as you have just discovered.
I have lost count of the number of students turning up on brush-up courses without the correct tools for the job then wonder why they can't answer a particular ATPL level question.
Reminder to US students that programmable calculators are NOT allowed in exams here in UK. The Casio scientific calculator seems to be the de-facto standard. Most theory schools will either provide the equipment or at least give a recommendation.
On my ancient E6B ram rise not possible but as previous post it's simple with a CRP-5. I too get around -47.