Question about HP 20s Calculator

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My HP 20S has 'BEGIN' on the display, how do I get it off?

My batteries were low, so my calculator was acting funny. I put new batteries in, and now I have 'BEGIN' on the display. I just want to perform general functions for now out to 4 decimal points. How do I get rid of this?

Posted by Patti Rawlick on


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Greg Cann

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Click the link below to get instructions to reset your calculator...

Posted on Jul 25, 2007


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Calculator does not turn off

According to the manual, either arrow should work. I would try the other arrow and the C key.

Good luck,

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20 hp manual pdf c00363319

Here is a link to Samson Cables (in Utah) that has some English copies for sale.
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The 20s uses PX76 batteries, also known as 675A and LR44 according to the manufacturer. The calculator uses three of them.

Oct 18, 2010 | HP 20s Calculator

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When I put new batteries in I have a reading of 0.0000 and I can't clear the screen or turn it off.

0.0000 is the calculator's clear screen. To turn it off, press the green arrow then the ON button.

Oct 12, 2010 | HP 20s Calculator

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HP12c showed expected display for low battery (star in lower left), put new batteries in and could not get any display at all. Took betteries out of mine (working great!) and now the one not working shows...

Resetting the calculator using the keyboardThe easiest reset is done from the keyboard. To reset the calculator, follow the procedures below in the order presented.
  1. Press ON to turn off the calculator.
  2. Press and hold [ - ] .
  3. Press and release ON .
  4. Release [ - ] .
  5. The screen will display “Pr Error
  6. The calculator will reset to the default settings, and the memory will be erased.

Aug 04, 2010 | HP 12c Calculator

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I need a manual on how to operate the calculator i have borrowed it from a friend and need to do my maths homework

The 20s is a "reverse polish notation" calculator. If you want to find 5x6, you will use the following keystrokes: [5] [ENTER] [6] [x]
The brackets are just to show the keys. The operator (the [X] button in this case) is applied to the last two numbers in the display.

Mar 02, 2010 | HP 20s Calculator

2 Answers

We need to download a guide and manual for an HP 20s calculator

I have not been able to find one in English, anywhere. I only found one in Spanish on the HP Spain website. If you want the link, post here and I will be happy to give it to you. Alternatively, you can look for it yourself on HPSpain.
And if you do not post back, I will understand that you ain't interested.


Nov 29, 2009 | HP 20s Calculator

1 Answer

HP 20S Calculator

If the calculator has locked up you should perform a reset.
  1. Press and hold the [C] (ON/OFF) key
  2. Press and hold the [LN] key (third key from the left on the top row).
  3. Release both keys simultaneously. T
  4. The calculator should display "0.00" (if the number of decimal places is set to two.)
If that does not bring it to life you should perform a full memory reset

  1. Press and hold the [C] (ON/OFF) key.
  2. Press and hold the first key from the left ( the Square root x key) and the first key from the right (the SIGMA+ key ) on the top row.
  3. Release all three keys at the same time.
  4. Calculator should display "ALL CLr".
  5. To clear the message press the [C] (ON/OFF).
  6. The calculator should display "0.00."
If the calculator does not respond as expected,
  • Remove the batteries, and
  • with a metallic coin (and what coin is not metallica) short-circuit the calculator's electrical terminals.
  • Maintain the coin for about ten seconds.
  • Replace the batteries (preferably fresh ones) respecting the diagram inside battery compartment.
  • The Calculator should display "ALL CLr".
  • To clear the message press the [C] (ON/OFF).
  • The calculator should display "0.00."
If the calculator does not respond to the foregoing procedures, remove the batteries and leave them out of the calculator for 24 to 48 hours to drain capacitors.

If it continues to malfunction, it will need to be repaired. One repair shop in Pennsylvania, USA has a website at Here is the link . You should contact them.

Hope it helps.
Thank you for rating the solution.

Sep 03, 2008 | HP 20s Calculator

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