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Sorry, I need this ;) Well, maybe it helps someone decide whether to buy a 30b or not.

I've been using the 30b at work for two weeks now and I'm not so happy with it.

I knew there's a depreciation bug. However, I've read somewhere that it only affects the SOYD and DDB method calculation. In Germany, we only have Sline and DecBal (and a third method that doesn't matter), so I thought maybe I'm lucky and those two methods work. They don't. Okay, Sline does, DecBal doesn't. Grrr.

How can something like that even happen? And why doesn't HP offer a new firmware at least? It can't be so difficult to solve that problem.

The 30b has its good sides - the keyboard is pretty good, the display is nice, the size is okay and the front looks good.

Who thought the glossy back would be a good idea? And the pouch... someone here said it's better than the 17bII+ pouch! Hard to believe, because my 30b pouch already has scratches just from being in my briefcase.

It is a very fast calculator, I admit.

Although it's smaller than my 30b, I don't like carrying it around. It rests on my desk while at work.

The 19BII solver is very easy to use. I think I really love it ;) The 30b's solver... well, I'm looking forward to finding out how it all works, one day...

The manual that comes with the machine is a joke. There's another manual available online, It's English, only, which kinda sucks, because I don't know many of the financial terms. How much would it cost to make the manual available in other languages? Less than 10 cents per unit sold, I suppose, probably a lot less than that.

Although the manual is available online, only, the layout is made for printing. Why? The manual is really hard to read on my ebook reader or phone. Well, it should at least look good on the ereader.

It's still a good machine, if depreciations aren't important to you. And Marcus said this problem could maybe be solved. I'll try to find out how.

Okay, Sline does, DecBal doesn't. Grrr.

Can you give a simple example? Let's say a good that cost 100€ to be depreciated over 5 years? A table with correct and bad values would help.

BTW, I was in Waldkirch but had barely time to see a very good friend in Freiburg. Maybe we can meet next time.

The 30b has its good sides

Agreed! The inner side is good to run the wp34s firmware. The outer side is good to stick a wp34s overlay on :-)

> I knew there's a depreciation bug.

> DecBal doesn't. Grrr.

One of the many reason why I prefer my own financial program.


HP 50G Financial Mathematics: Annuity / Pension / Investment

It covers what *I* need but, of course, it could be expanded easily
for further financial calculations.

And I wrote a German and English manual that describes *exactly*
what the program does ;-)

Programmbeschreibung Finanzmathematik

But - as pointed out various times - the HP calculator group simply
does not want to be successful with the HP 50g.

Why, that remains their mystery...





Agreed! The inner side is good to run the wp34s firmware. The outer side is good to stick a wp34s overlay on :-)

Ha ha hahahahah ha!

Edited: 15 Apr 2012, 6:50 p.m.


Agreed! The inner side is good to run the wp34s firmware. The outer side is good to stick a wp34s overlay on :-)

I thought someone was gonna come up with that! :)

Good one


The 19BII solver is very easy to use. I think I really love it ;) The 30b's solver... well, I'm looking forward to finding out how it all works, one day...

You have been warned ;-P.

About the new firmware: I though there was an update Tim was sending out on request? Anyone knows?

Sure. DecBal for 100€ over 5 years at 25% bought in January:

Year HP... and what it should be

Wait... WTF? Yesterday I got results that looked at least a little bit realistic, especially when starting at the beginning of the year. But now... Okay, once again.

Year HP...   and what it should be

1 50,00 25,00

2 25,00 18,75

3 12,50 14,06

4 6,25 10,55

5 6,25 31,64

Now let's start in July:

Year HP...
1 25,00

2 37,50

3 18,75

4 9,38

5 4,69

6 3,13

That's a total of 98,45!

When you compare the German Depreciation Rules with the American method(s) you can see differences imposed by the respective fiscal laws. E. g., in Germany the rate can never be greater than 20% while in the U.S. 40% is perfectly legal. This might explain the differences.

It should be a simple task to create a 30b program to obey the German depreciation rules.

It looks like the depreciation rates depend on the factor which is initialized at 200%. This would result in a 40% rate for year 1. This is not legal here in Germany. Have you switched you calculator to German?

E. g., in Germany the rate can never be greater than 20% while in the U.S. 40% is perfectly legal. This might explain the differences.

Unfortunately, it doesn't. The rate is determined by what you type into the calculator, only. It even has to be that way because the laws are always changing. In fact, at the moment DecBal is not allowed in Germany for new goods. In the past, the maximum DecBal rate has been 20%, 25% or even 30%, but never more than x times the Sline rate.

I suppose the 40% in your example result from using DDB, which is not the kind of DecBal used in Germany.

I'm getting exactly your "should be"-values, on the 30b as well as on the 17bii.

What I'm entering on the 30b is:


Nutzungsdauer 5.0000

Anfang 1,0000

Selbstkosten 100,0000

Restwert 0,0000

Faktor 125,000

Jahr 1 (2,3,4,5)

Abschreibung 25,0000 (18,7500 14,0625 10,5469 31,6406)

The 40% results from the default setting FACT=200.

Hm, you really shouldn't - because the depreciation values in your example are wrong.

Did you use a Faktor of 125 to get my "should be" values? If yes, you've found a nice workaround - thanks a lot! Just enter half the factor to get the right results.

That solves at least one part of the problem. Depreciations beginning with a partial year will still be miscalculated.

I'm starting to wonder whether it's my mistake. Although... nah. Okay, DecBal seems to be very uncommon in the USA. The 30b DecBal calculation starts like a DDB calculation. Maybe they've used the DDB routine to start with and no one noticed they've forgotten not to double the percentage because they're all used to the higher values? Doesn't sound right...

I'm off again, will have a closer look at all this tonight.

Straight line depreciation for 5 years would mean 20% per year, which would mean a DecBal factor of 100 (% that is). Your DecBal depreciation rate of 25% is 125% of 20, thus the factor is 125. The factor you have to enter here is allways the percentage of the rate that the straight line depreciation yields, which is calculated at 1/(years of use). The default DecBal factor 200 being the usual double (or 200%) of the straight line rate, that is most commonly applied.

Edited: 17 Apr 2012, 7:55 a.m. after one or more responses were posted

On the one hand, that would explain everything. Thank you, Alexander! By the way, the manual only says "The declining balance factor as a percentage. This is used for declining balance and declining balance crossover methods only.". Unfortunately, it doesn't say the percentage of what.

On the other hand, it's neither logical nor practical for several reasons. Well, at least in Germany. I'll read up on the laws in the USA.

However, I have to admit, it's depending on one's point of view! For example for assets bought in 2010 I've thought:

Depreciate 25% in year 1 if that's not more than 2.5x the Sline rate!

Instead, I could think:

Depreciate 2.5x the Sline rate in year 1, unless that's more than 25% of the cost of the asset!

Now it seems to make sense. However, the 2.5x bit is only relevant for assets with an expected life of more than 10 years (Sline 100%/10*2.5). Almost all assets I've had have an expected life of less than 10 years.

Let me make a practical example of how impractical it is.

You buy an asset in 2010 with depreciable costs of 10,000€, an expected life of 7 years and a salvage value of 0€ (no need to make it more complicated than it is).

The Sline rate is 1/7=0.142857... or roughly 14%. DecBal would be those 14%*2.5=35%. That would be about 3,571€ which is clearly more than 25% of the cost of the asset!

To get the right rates in the 30b, I now have to calculate the percentage of the Sline rate that equals 25% of the asset cost - 7/4=1,75 (7 years/(100/25) so to speak). Enter those 175 as the factor and - tadaa! - you'll get the right results!

Seriously? Is that the way I'm supposed to calculate my depreciations? I don't think so!

If there's a better way without making my own DecBal program, please tell me.

You could always try something different.

By the way - using this "175" method, depreciations beginning with a partial year almost work - only the last year is wrong (and most of the other data except the depreciations themselves).

Cost 10,000€, Life 7, Start 7, Salvage 0€.

What it should be:

Yr.   Depr.     Value
1 1250.00 8750.00
2 2187.50 6562.50
3 1640.63 4921.87
4 1230.47 3691.40
5 922.85 2768.55
6 692.14 2076.41
7 519.10 1557.31
8 1557.31 0.00


Yr.   Depr.     Value
1 1250.00 7500.00 (what?)
2 2157.50 5625.00 (again?)
3 1640.63 4218.75
4 1230.47 3164.06
5 922.85 2373.05
6 692.14 1779.79
7 519.10 1334.84
8 1334.84 0.00

The values are wrong. The values shown are from a full first year (Start 1) DecBal calculation. Internally, the 30b uses the right values for all years but the last one.

Read up on depreciation methods in wikipedia, it will become much clearer to you.

Straight line means: 5 years of life and one fifth depreciation of the original value per year. 7 years of life and one seventh depreciation of the value per year. And so on.

Declining balance depreciation is a more 'natural' approach. Commonly the depreciation rate from the straight line approach is just doubled, thus the factor 200%. Take your 7 year example: straight line depreciation rate is roughly 14%. If you want the results for the most commonly used declining balance method, you would calculate with the double of 14%, which is 28%. For that you only have to set the factor in DecBal to 200.

Let's take another look at your 100 €, 5 years depreciation example from above: straight line deprecation is one fifth (20%) of the original value per year, so after five years it is completely depreciated. The usually used declining balance approach would use 40% (instead of your 25%) and you would set the factor in DecBal to 200 (because 40 is 200% of 20). To calculate the results in your example you set it to 125, because 25 is 125% of 20 (remember 20% being the 1/5th of the straight line method).

Edited: 17 Apr 2012, 7:57 a.m. after one or more responses were posted

The Depreciation issue with the 30b is quite real and it doesn't matter whose rules you follow, whether it is US MACRS or US GAAP, or IFRS, or otherwise (I think the problem also affects the 20b). The 30b always fails on DBXover, SOYD, and it fails on all depreciation methods when partial periods are being used. There is a problem with the arithmetic involved and I have already addressed this is issue with Tim Wessman at HP. A fix is currently in the works and it should hopefully be available soon, in addition to fixes for other bugs that I have addressed with him.

I have tried to write a program as a workaround, but I have not been very successful as the programming paradigm on the 30b does not lend itself well to creating a depreciation program. The best thing to do in the meantime, while the fix is being developed, is to use a program like Excel, which, I think, does a much better job of dealing with depreciation than any financial calculator can. I hope this is helpful.



There's no need for me to read up on depreciation in the german wikipedia.

You seem to have your information from some US source or so.
For example when you say:

The usually used declining balance approach would use 40% (instead of your 25%)...

Using 40% has never been allowed in Germany! For an asset bought in 2010, 25% is definitely the maximum. Because 25% was the maximum set by the fiscal authority.

In other years it's been 20% or 30% or sometimes there was no DecBal allowed at all.

You can find more information about how it works in wikipedia.

If you don't believe me, use this depreciation calculator (or any other "AfA-Rechner") to compare it to the results from your calculator. They will be different, unless you use my "175" method. You'll also notice that whatever you do, you'll never get 40%.

Hope to have understood the matter, if not I beg your pardon for the intrusion

as from the previous replies of Alexander:
The declining balance method is a combination of the straight line and the fixed percentage methods. For this method it is customary to use a declining balance factor.
A straight line percentage is calculated: for an aset that is depreciated over five years, this would be 20 %.

Then, depending on the declining balance factor (between 100 % and 200 %), the fixed percentage is calculated: for a 200 % or a "double declining" factor, the fixed percentage would be 20 % x 200 % = 40 %.

In your case is 25% and maybe the "factor" to set will be 25:20 % =125 (!)

I think the matter we are discussing is away of the laws of each country, maybe we are trying to understand which is the method that the calculator uses for calculating the depreciation (declining balance)and how to correctly input the datas (this is the problem as I could understand)

Edited: 16 Apr 2012, 7:09 p.m.

Thanks, Mark.

I wanted DBXover. But as soon as you realise the Xover usually happens in the year 100/DecBalPercentage*, it's not so terrible not having it.

Example: DecBal rate is 25% means you switch from DecBal to Sline in year 100/25=4. I wish someone had told me this 10 years ago, I just found out recently...

There are two issues here that you seem to mix:

a) When you start depreciation in January, the mathematical results of the 30b are correct, but you still have to apply the tax laws of your country yourself. So, if the mathematically correct result is greater than 20% (or whatever percentage applies) you can't use it. German AfA-calculators take that into account. If you want the 30b to take that into account as well, you would have to write a program.

b) Start at any other month than January and you run into the 30b's bug, as described below in this thread.

Edited: 17 Apr 2012, 7:57 a.m.

Hello Timo,

it seems to be a great ironic story about the "business calculator" HP 30b. The depreciation "DecBal" can be easyly calculated with the RPN and three of the four stacks.

for example:

100  INPUT INPUT 0.2 (20 %) * -  

Before you key in "-" you can also take the half or the third, when you are starting in between the year.

You get: 80


You get: 64

and so on...

But what is the mistake?: it is a systematical error, the value after depreciation is too small: You can calulate it, but not within the "DecBal" procedure. And how others have mentioned,
these built-in functions are not very handy to use it in programs, if at all it is possible.

If p is the fraction of the value for depreciation, then is 1 - p the rest fraction of the value that can be written as a/b.

And the every false value you get from HP 30b is 2a/(a+b) smaller then the correct value.


Edited: 17 Apr 2012, 5:43 p.m.

Hello folks,

a little errata: unfortunaly the erronous quotient depends on the fractional year, too.

So you get for the beginning of the depreciation in the seventh month with a rate of 30 %: a factor of 14/17, if you begin in the nineth month: 28/31, so my "law" only is correct for a half year.


The problem is, the 30b has already applied some other country's tax laws or customs!

You see, DecBal is per definition a method of depreciation whereby a rate is applied to the remaining balance to derive the depreciation deduction.

Everything else is just tax laws of one's country. It seems that taking the Sline rate as a basis of calculating the DecBal rate is some country specific thing that the 30b automatically applies.

It would be much more logical being able to enter an absolute rate, but, well, since that's not the way they do it in the USA...

This renders the 30b DecBal function pretty much useless for countries with a maximum declining balance as for example and AFAIK Germany, Danmark, Bulgaria, Austria, Finnland, Sweden...

The same kinda applies to France, Canada and Russia - but for certain reasons it doesn't have any effect there at the moment.

And in Soviet Russia the asset depreciates you.

HP should have made the DecBal function work for as many countries as possible. There are two ways:

- Let the user choose between inputting a factor relative to the Sline factor or an absolute one.

- Let the user set a maximum DecBal factor.

But I guess customers outside the USA just aren't so important... Come on, we're not talking about just a bunch of people. It's not like asking them to make a Sline to DecBal Xover function just for one country.

(And again, just for the sake of it, inputting an absolute factor would be so much better.)

Absolut value input would be easy, indeed. But calculating the factor needed isn't that sophisticated:

Given 25% is the maximum rate, the factor for DecBal is 25*n (years of total use)

For 5 years factor=125 (as you remember from above)

For 7 years factor=175

For 10 years factor=250

and so on...

The partial year problem is easily solved by calculating the first depreciation by hand and entering the "Buchwert" as the asset's inital value in DecBal. You only have to note that year 1 in DecBal is the first whole year in reality, so actually year 2.

And finally, gathering from other sources, that the 30b is out of stock and thus maybe discontinued and that depreciation in Germany since 2011 is only by straight line method: who cares! ;-)