Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question. What programming task do you have to do with your HP calculator?

Try doingLBL X (where LBL is the key marked that way, and X is the key marked X). In other words, the whole formula would be 18000 / pi / LBL X I think.) Let me know how that works.

Maybe LBL X has to be at the beginning of the line. Can you redo the forumula so that is how it is entered? or, try entering it that way (as a test) even if the formula will come out incorrectly, just to see if it will enter that way.

Then I frankly do not know why it won't. Make sure that you are in PRGM mode, first, of course, before entering the keys... otherwise, it's a standard operation. I am puzzled what else to suggest, so I have Opted Out, with apologies.

Hello my name is***** look forward to assisting and am very sorry to hear that you are having this problem. The formula solver is a little different on this model than it is on TI calculators. Please see this guide it explains how to use it as well as how to input in this case X: http://h20331.www2.hp.com/Hpsub/downloads/35_24_Formula_Solver_1.pdf If this did not work, please come back and let me know what happened when you tried it by clicking on reply to expert so we can continue. If it did work, please don’t forget to leave a positive rating - it is greatly appreciated.