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HP 19BII Frequently Asked Questions
Over the years, I have received many questions about financial calculators. I will compile a list of the most frequently asked questions here.
Q: My HP 19BII is showing a comma instead of a decimal point. How do I fix this problem?
A: This is easily the most commonly asked question. I wish I knew how people got themselves into this situation, because it seems unlikely that it could happen by accident. Here is how to solve the problem: Press DISP and then choose . (decimal point) from the menu.
A little background on this. In the U.S. and many other countries, we use a decimal point as the radix point (or decimal separator) and a comma as the thousands separator. Many other countries do exactly the opposite. For a complete list, see the decimal separator article on Wikipedia. Interestingly, as far as I can tell this has nothing to do with the side of the road on which you drive. Obviously, the 19BII was created with worldwide users in mind.
Q: How do I change the number of decimal places that are displayed?
A: Simply press DISP FIX from the menu and then a number key. For example, to display five decimal places, press DISP FIX 5 INPUT.
Q: How do I enter a negative number into one of the TVM keys on the HP 19BII?
A: The way to do it is by using the +/- (change sign) key. For example, to enter -1,000 into FV, press 1000 +/- FV.
Q: How do I change the HP 19BII so that it uses RPN data entry instead of algebraic (or vice versa)?
A: First, many people aren’t familiar with RPN and therefore often don’t know that most calculators use algebraic data entry. So, think of algebraic as “normal calculator” mode. RPN is a very different (and, I would argue, far superior) method of data entry — it makes life much easier when entering equations. In any case, if your 19BII is in the wrong mode you can fix it by pressing Shift DISP MORE and then choosing either ALG or RPN from the menu.
Q: How do I find roots other than square roots using the HP 19BII?
A: In finance it seems that we are forever calculating various roots (cube root, fourth root, 365th root, etc). Fortunately, this is pretty simple to do if you can remember a simple mathematical rule:
$$\sqrt[N]{X} = {X^{\frac{1}{N}}}$$
So, to calculate the 5th root of 100, we simply raise 100 to the 1/5th power. To do this on the 19BII in:
| Mode | Keystrokes |
| ALG mode | 100 ^ 5 1/x = |
| RPN mode | 100 INPUT 5 1/x ^ |
In this example, the 5th root of 100 equals 2.51189. Using this technique you can calculate any root.
Q: My calculator only has a key to calculate natural logarithms. How do I calculate logarithms to other bases (say, base 10)?
A: Most often, in finance, we use natural logarithms (base e), usually abbreviated as Ln(x). However, sometimes we need to use other bases. Converting from base e to any other base can be done with the following formula (I’m converting to base 10):
$$Lo{g_{10}}\left( X \right) = \frac{{Ln\left( X \right)}}{{Ln\left( {10} \right)}}$$
So, just calculate the natural log of your number, and then divide it by the natural log of the new base. For example, Log10(3) = Ln(3)/Ln(10) = 0.478. Note that the 19BII does have a LOG function in the math menu for calculating base 10 logarithms. Press SHIFT % LOGS to see the logarithmic functions. Still, if you need another base the above formula will work — just change the 10 to your selected base.