Message #1 Posted by Mike T. on 20 Oct 2009, 5:19 p.m. started a recent thread on calculation of the Fibonacci sequence with the following:

Quote:The HP-33s in algebraic mode wins for ease from the keyboard with the following procedure:

Following an interesting discussion earlier this evening I thought it might be fun to see just how few keystrokes you would need to calculate successive terms of the Fibonacci Sequence, preferably without using any storage registers...I doubt it I have the best solution but thought the answer I came up with demonstrated really nicely why I like my old RPN calculator so much and that it would be interesting so see what other people came up with.

Start with a one in 'x' - all other registers zero.

With a one in "x' and zero in 'y' press + x<>y repeatedly and read the lower display after each + to see the sequence

1 1 2 3 5 8 13 and so on

and also notice that the sequence builds as a sum in the upper display as well but with a unwanted leading 1 + 0.

*Edited: 25 Oct 2009, 9:36 p.m. *