Which Calculator to Buy for Bachillerato and the PAU in Valencia
One purchase that serves you from 1st year of Bachillerato to your last PAU exam. What the rules allow, which model I recommend and how to get the most out of it.
Every September the same scene repeats. A student starts 1st year of Bachillerato (the two years of upper secondary school before university) with the calculator they used in ESO, or one a friend lent them. Then, in the first topic on matrices or the first normal distribution, they realise it is not enough. Buying well once saves you money and, above all, time in the PAU (Spain's university entrance exam, also called Selectividad).
Casio fx-991SP CW (ClassWiz)
- More than 560 functions
- Matrices and vectors up to 4×4
- Systems of up to 4 unknowns
- Probability distributions
- Spreadsheet and table of values
- Solar panel + button battery
- About €43–53 in online shops
What the Valencian PAU rules say
The rule has been the same for years: a calculator is allowed as long as it is not graphing or programmable, does not perform symbolic calculation and cannot store text or formulas. This is set out in the official specifications for the MACS II exam and in the calculator agreement published by the UPV (Polytechnic University of Valencia) for the PAU.
Under those conditions, the fx-991SP CW passes without problems. Casio Educación explicitly lists it among the calculators permitted in the Valencian Community, alongside its smaller sibling, the fx-570SP CW.
Careful if you sit the exam elsewhere
Not all regions are the same. According to Casio, Madrid, Aragón, Murcia, Asturias, Castilla y León, La Rioja, Navarra and the País Vasco limit use to more basic models, without equation solving. If you will sit the PAU in another region, check its rules before you buy.
What you will actually use it for
Nobody in the PAU will give you marks for a result without working. The calculator does not replace the working out: it is for checking. And checking well is what separates a 7 from a 9. These are the uses that save the most time:
| Block | What you do by hand | What you check with the calculator |
|---|---|---|
| Matrices | Inverse by the adjugate method, matrix equations | That A·A⁻¹ gives the identity and the value of the determinant |
| Systems | Discussion with Rouché, Gauss or Cramer | That the solution you got is the correct one |
| Probability | Setting up and standardising | Normal areas and binomial probabilities without tables |
| Analysis | Derivatives, limits and integrals | The numerical value of a definite integral and tables of values for sketching |
| Geometry | Setting up lines and planes | Dot and cross products using the vectors mode |
In Maths II the probability and statistics exercise is compulsory, and in MACS II the statistics question is worth 3 points. Being able to calculate a normal probability on the calculator in ten seconds gives you back time for the rest of the exam.
What about the fx-570SP CW?
It is also allowed in the Valencian PAU and is usually a little cheaper. The most visible difference is the power: the 570SP CW runs only on an AAA battery, while the 991SP CW combines a solar panel and a button battery. If budget is tight, it is a valid option; compare the functions of each in the shop. For both years of Bachillerato, my recommendation is still the 991SP CW.
What if you study the IB?
That is a different story. The IB maths papers use a graphing calculator, which is banned in the PAU. If you do the IB and also sit the PAU, you need both. I explain this in detail in which graphing calculator to buy for IB Maths.
Five mistakes I see every year
- Degrees instead of radians. If you differentiate or integrate trigonometric functions with the calculator in degrees, everything comes out wrong. Before an Analysis exam, check the mode.
- Rounding in the middle of a problem. Store intermediate results in memory and only round at the end.
- Using it for the first time on exam day. If you do not know where the distributions menu is, it will not save you any time. Use it from the first topic.
- Writing only the answer. The PAU marks the working. The calculator checks; the working goes on paper.
- Bringing a model that is not allowed. A graphing or programmable calculator can be confiscated. If you are unsure about a model, check the rules first.
Frequently asked questions
Is the Casio fx-991SP CW allowed in the Valencian PAU?
Yes. In the Valencian Community scientific calculators such as the fx-991SP CW are allowed, as long as they are not graphing or programmable, do not perform symbolic calculation and cannot store text or formulas.
Is a calculator from ESO good enough?
For basic operations, yes. But basic models do not solve systems, do not work with matrices and do not calculate distributions, which is exactly what helps most when checking Bachillerato work.
Can I take a graphing calculator to the PAU?
No. Graphing and programmable calculators are not allowed. If you study the IB and also sit the PAU, you will need both.
What if I sit the PAU outside the Valencian Community?
Check that region's rules. According to Casio, regions such as Madrid, Aragón or Murcia are stricter and limit use to more basic models.
Sources
- Casio Educación: calculators permitted in the PAU.
- UPV: agreement on calculators in the PAU (PDF).
- MACS II: exam specifications and marking criteria (PAU 2026).
- Casio: specifications of the fx-570SP CW and fx-991SP CW.
Information updated 17 October 2026. Prices are indicative and change often. Always check the rules for your exam session.
Learn to use it from the first topic.
In class we work through each block with a calculator check, so you don't lose a minute in the PAU.
Message me on WhatsApp