HP Calculators Timeline » HP 10b II » HP10bii Troubleshooting

Why your calculator may be giving you the wrong answers?

  • Data Entry Error: a common mistake is in entering one number incorrectly, or in forgetting a step such as entering 0 in FV or PMT for certain calculations (which means that whatever number is in the key from the previous calculation will remain in the key's memory). You can always check what is stored in any particular key by pressing RCL and then the key. For example, to check what is in the PV key, you can press RCL PV If you get a number that doesn't make sense or is wrong, you can simply change this one number rather than starting again from the beginning. RCL can be used to figure out where a data entry problem occurred.
  • BEGIN appears on your calculator screen: if your calculator shows BEGIN on the bottom of the screen, you will get the wrong answers in most financial calculations. Mortgage payments are made in arrears or "not in advance" (i.e., you pay interest at the end of each month), compared to lease payments which are made in advance (i.e., you pay on the 1st of each month for the month ahead). You should set your calculator to "end-of-period" mode by pressing shift (the yellow key) BEG/END. This will remove BEGIN from your screen.
  • Decimal Places: the HP 10B/10BII calculator will display 0 - 10 decimal places. If you have the calculator set to show, say, 2 decimal places, it will automatically round off answers to the nearest cent. You don't want this setting because some calculations require a lot more accuracy and in others you need to be able to decide rounding for yourself. You should put your calculator in "floating decimal" mode which shows the most significant decimals possible -- press shift DISP .{period}
  • Batteries: if the batteries are dying, your calculator screen will dim and eventually a little battery symbol will show in the bottom right corner. However, your calculator won't start to give wrong answers as the batteries run out! See your HP 10B/10BII owner's manual for instructions on how to replace the batteries.
  • Self-test: if none of the above solves the problem, you can test the calculator using its self-test feature. If your calculator fails the self-test, before concluding it is defective, try running the self-test several times. It should come up with the same error message consistently - if it does not, then it is unlikely to be malfunctioning.

Updated On: 12.05.06

  1. On 04-May-2018, Sylvia wrote: 
    Hi guys, when I am calculating the i/g my calculator is saying "no solution"
    Your reply to Sylvia

  2. On 08-Dec-2017, Jim wrote: 
    I'm doing a sample test and the answer key tells me what to do. However, I'm still a couple dollars off. They say:
    Set your calculator for the beginning of the period. Input the following data:
    PMT = 1,200 (monthly payment)
    n = 198.72 (number of years between age 65 and 81.56,
    then
    multiplied by 12 months)
    i = .41667 (interest rate divided by 12)
    FV = 0 (enter 0 for the parameter you are not solving). Hit the PV (present value) button. We find that the present value of the
    monthly payments is $161,759.
    Their answer = $161,759. I have it set to 1 payment. My answer = 162,624. What am I missing?
    Your reply to Jim
    • On 02-Mar-2018, Celia replied: 
      JIM!!! did you ever figure this out? we are working on the EXACT problem and i died when i saw your question. We are having the SAME issue. What did you find out? was it a booklet typo?
      Your reply to Celia

  3. On 16-Sep-2017, Shani wrote: 
    My hphone calculator is calculating the npv and irr wrong what is the problem my battery is also running low pls explain
    Your reply to Shani

  4. On 26-May-2017, Jones wrote: 
    my calculator is giving me a wrong answer when trying to calculate NPV. the following are the cash-flows. YR 0 =(70000) YR 1 to YR 5 =21000 and I/YR is 12%. if i enter these cash-flows when i recall NPV I'm getting 31.92 as NPV and internal Rate of Return as 182.86. if i calculate manually I'm getting the correct answers. is something wrong with my calculator. Please help me. Thank you in advance
    Your reply to Jones

  5. On 01-Mar-2017, Amanda wrote: 
    My calculator is giving me wrong answers when entering N=240, I/YR=0.33, PV=-350,000, FV=0 and PMT is 2113.56 instead of 2120.93.
    I have tried to play around with it and used N=20 x 12 , I/YR= 4 / 12 , PV=-350,000, FV=0 and PMT was correct @ 2120.93.
    The P/YR was already being set to 1 payment per year.
    Cheers.
    Your reply to Amanda

  6. On 23-Nov-2015, Yewande wrote: 
    Troy invested 200,000 today. The investment will earn 6% for 5years with no funds withdrawn. In 5yrs the amount in the investment fund is. the answer is 267,645.12 but can't get that on my hp10bII I keep getting 205,050.25, what is wrong
    Your reply to Yewande
    • On 18-Mar-2016, Gn replied: 
      I get the same thing. Anyone know what we're doing wrong?
      Your reply to Gn
      • On 27-Jul-2016, Anonymous replied: 
        The assumption in your investment is based on annual investment of 6%. Therefore, you need to set the payment per year (P/YR) value to 1. (Reply)

  7. On 08-Oct-2015, Randy wrote: 
    I am trying to set the floating decimal. My calculator will show eg. 1.234,56 instead it should be 1,234.56 what do I need to do to correct the problem Thx
    Your reply to Randy
    • On 27-Jul-2016, Anonymous replied: 
      [orange] [=] [n, where n is the number of decimal points]
      Your reply to Anonymous

  8. On 10-Apr-2015, Siya wrote: 
    I am trying to calculate yield to maturity but I keep getting the wrong answer
    Your reply to Siya

  9. On 25-Nov-2014, Anonymous wrote: 
    Im solving for N periods given PV 125,000; i 5; pmt 602.75. correct answer is 479 but it keeps telling its 150. Please help
    Your reply to Anonymous
    • On 22-Dec-2014, Peter Tong replied: 
      By factory default, the calc is set to 12P/YR. It will show the answer of -150. If you set the calc to 1 P/YR, it will show the N as -49.82 Here is how you set the HP10bII+ calculator to 1 P/YR.
      Your reply to Peter Tong

  10. On 10-Apr-2014, Michael wrote: 
    How do you replace the batteries in an HP10B II calculator?
    Your reply to Michael

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