I am due to take my BA7 in 3 weeks time and I had exactly the same problem as you with regards to the bank reconcilliation.
My solution was to quickly write down the figures on a piece of scrap paper so that I had a hard copy to work from. This actually only takes a couple of minutes and I found it a quicker solution then trying to memorise which figures balanced from the screen.
I would strongly recommend purchasing the ICB mock as well as this will be very similar to the real test. I completed mine with 1 minute to spare so no chance of going back over my answers. I passed this mock but another advantage of taking it is that you have access to the correct answers afterwards. I found this very useful and you can also refer back to it at any time which I feel is a good revision tool.
Good luck with your BA7