Why is My HP RPN Operation Displaying Unexpected Results?

[cwalken]

HP strange RPN operation?

I just find an odd behavior on my hp rpn operation. Can someone try the following sequence of entry and explain to me this strange behavior?

Press 5 (any number will do).
Press 'Enter' (this should duplicate 5 to x an y stacks)
Press 'Enter' again (duplicate 5 again so now x,y and z stack are all 5)
Press 'RDn' to rotate stack 4 times (this should bring the stack configuration back to the same, x,y and z stack are all 5. The stack should read (5,5,5,0) for (x,y,z,t).
Now press 10 and then *.

Normally, I would expect the stack to be (50, 5, 5, 0) for (X, Y, Z, T). But if you follow the above step, you will get (50, 5, 5 ,5). Am I missing something here?

 

[Jim1138]

That is the correct behavior. The T register is not zeroed, but remains the same. If you press 2 / enter / enter / enter, then press + many times, you will get 2, 4, 6, 8, 10, 12, 14, 16...

 

[quicknote]

It is difficult to provide a definitive answer without more information about the specific HP calculator model and its RPN operation. However, one possible explanation for this behavior could be that the calculator is following a different order of operations than you are expecting. For example, it may be prioritizing the multiplication operation before the duplication operation, resulting in the stack being (50, 5, 5, 5) instead of (50, 5, 5, 0). Without knowing more about the specific calculator and its RPN operation, it is difficult to provide a definitive explanation. It may be helpful to consult the calculator's manual or reach out to the manufacturer for clarification.