Assuming you are talking about the 10bII+, you can actually completely ignore that example!
It was leftover from when we did the conversion from the 10bII into the 10bII+. The 10bII did not have net future value and so that long example was trying to show how to manually calculate it. The 10bII+ actually does have NFV though by doing a SWAP on the NPV calculation. So you actually can do the whole thing in 1 step now. The example was meant to be deleted, but the person working on the documentation missed deleting the remaining part at the bottom of that page.
I beleive we did remove it in a later editon, but I'm not certain if it ever made it out there. I will check on that to be sure. Thanks for the input!
Although I work for the HP calculator group as a head developer of the HP Prime, the views and opinions I post here are my own.