We have discussed several times hp financial calculators, but we have not talked about scientific calculators for a long time.
We have 4 models in the roster - although one of them is difficult to find. I even don’t have a unit of it, and I think I’m not missing too much.
These models are the 10sII+, the 300sII+, the hp30s and the hp35s. It is a pity that the hp15c LE, which was built in limited numbers, is not anymore in production. Used models sell for over 150€.
If you are in the market to buy a scientific calculator, you should also consider graphical calculator alternatives. They can do so much more, and for not so much money, when you consider the offers you can get for older models.
Let’s start with the cheaper ones: the hp10sII+ and hp300sII+. And let’s get it out from the beginning: THESE MACHINES ARE NOT RPN. Moreover, the logic in the machines has been seen in at least another two brands- it seems to be a rebadged design. This doesn’t mean that these are bad - far from it. I would have recommended against the previous units (hp10s and hp300s): they had basically the same logic, but they were cases in extremely ugly bodies, and the screen quality was not fantastic, to say the least. But these two units are much better: the screen has much more contrast, and the casing shows iphone 5 traits of design. You can see the pictures and judge for yourself. The 300sII+ is more advanced and has a greater range of functions, and, at 15€, is a safe bet.
The HP30s we do not carry. We don’t think it is good enough to bear the HP logo - and the price is not rock bottom. Pass.
The HP35s is one of the most beautiful calculators ever produced. Its black background, its clever use of colors for the different key functions, its legible screen with two lines of dot-matrix text, and its cursors to operate calculator and navigate the menus, make it really appealing. And it has real RPN and algebraic entry, and all the important scientific functions you may need, including complex and solving simple equation systems.