Your formulaYour operation, exactly as the calculator understands it, appears here
M · a number is stored in memory
Your latest operations
Exam mode is designed for a computer with a mouse, as at SENASA: the keys have their real size and are small for a finger.
Free, no sign-up. Your calculations never leave your device. Independent study tool, not official.
What the SENASA exam calculator is like
You use it with the mouse
The official calculator appears on screen and you click it button by button: the version SENASA publishes does not respond to the keyboard. It is the calculation tool SENASA provides for the exam, so arriving with trained fingers saves minutes and nerves.
It works in degrees
You type the number first and press the function second: 30sin gives 0.5. Results of sin, cos, tan and their inverses are rounded to 4 decimals.
Phone-style keypad
1 2 3 is at the top and 7 8 9 at the bottom, the opposite of a normal calculator. It is the most common slip on exam day.
Every quirk of the official SENASA calculator
We compared this replica with the official calculator key by key and catalogued everything that behaves unexpectedly. Here it does exactly what it does in the exam, so that you meet it at home first. Each button replays it on the calculator above. The eight serious ones fit on a printable golden rules sheet.
They give you a wrong result with no warning
1. Adding a sin, cos or tan result glues the numbers together
If the result of sin, cos, tan, asin, acos or atan is the second number in an addition, the calculator writes it after the first one instead of adding it. The same happens if you bring it back from memory with MR or put it in parentheses.
How to avoid it: start with the function (30 sin + 1 =) or multiply it by 1 (1 + 30 sin * 1 =). It does not happen with subtraction, multiplication or division.
2. Memory M+ also glues sin, cos and tan results
M+ with a trig result on the screen does not add: it glues it to whatever was in memory. And the memory stays «contaminated»: the next M+ glues too, even with a normal number.
2 M+ 30 sin M+ MR → 20.5(correct: 2.5) 30 sin M+ 2 M+ MR → 0.50002(correct: 2.5)
How to avoid it: store with MS, or convert the result first with * 1 =. M- does subtract properly. Press MC to clean a contaminated memory.
3. A subtraction followed by × or ÷ and then another + or −
When a subtraction is pending, then a multiplication or division, and then another addition or subtraction, the calculator groups it wrongly: it subtracts everything that comes after.
How to avoid it: use parentheses (10 - ( 3 * 2 ) + 1 =) or press = between steps. In long chains mixing subtractions with × or ÷, when in doubt, use parentheses.
4. Trig functions are rounded to 4 decimals
The result is rounded to 4 decimals and the calculator keeps working with the rounded value. With small angles the error shows.
1 tan → 0.0175(true: 0.017455) 1 tan * 60 = → 1.05(true: 1.047)
How to avoid it: you cannot. Exam answers are calculated with more precision: pick the closest option and do not worry if the last decimal differs.
5. The sign is lost if you press +/- before the number
+/- changes the sign of whatever is on the screen at that moment. If you press it before typing the number, the sign disappears as soon as you type.
8 * +/- 2 = → 16.(you wanted −16)
How to avoid it: number first, sign second: 8 * 2 +/- =.
6. No implied multiplication: a number next to π, e, MR or a parenthesis is lost
This calculator has no implied multiplication. If you type a number and then a constant, the memory or a parenthesis, the previous number is simply discarded.
How to avoid it: always press *: 2 * π =, 5 * ( 2 + 3 ) =.
7. Two operations in a row do not replace each other
On many calculators, if you press the wrong operation you just press the right one. Not here: the calculator keeps both and repeats the previous number.
How to avoid it: if you press the wrong operation, press C and start again.
8. tan 90 gives no error
The tangent of 90° does not exist, but the calculator shows a huge number with no warning. Any calculation after it will be nonsense.
90 tan → 16331239353195370.
How to avoid it: if you see a 17-digit number after a tangent, check the angle.
It works differently from your usual calculator
The function goes after the number
For the sine of 30 you press 30 and then sin. The other way round, sin is applied to the 0 on the screen and the 30 replaces it.
There is no key to delete a digit, but there is a trick
If you mistype a number, press ( and type the right one: the wrong number is discarded. 5 + 23 ( 24 = gives 29. The = closes the parenthesis by itself.
It only accepts 11 digits per number
From the 12th digit on it stops typing with no warning. With decimals, at most 10 digits after «0.».
Pressing = several times does not repeat the operation
2 + 3 = = is still 5. You cannot use it to add repeatedly as on other calculators.
A «)» with no «(» works out everything pending
2 + 3 ) * 4 = gives 20: the ) acts as an intermediate =. And the other way round: = closes all open parentheses by itself.
With 12 pending operations the calculator freezes
Every waiting operation and every open parenthesis takes a slot, and there are only 12. With 6 nested parentheses and an operation before each one they fill up: from then on the screen stops updating with =, ) and the operations, and the calculator seems dead. 1 * ( 2 + ( 3 * ( 4 + ( 5 * ( 6 + ( 7 = is left showing 7 instead of 209. Press C to get out. In long calculations, work in parts and save results with MS.
C does not clear the memory, and the screen does not show that something is stored
Only MC clears the memory. In the exam there is no «M» on the screen: before using M+, press MC if you are not sure.
After an Error in the middle of an operation, everything keeps giving Error
1 / 0 + 5 = gives Error even if you keep typing. You have to press C and start again.
There is no power key x^y and no scientific notation key
Only x^2 exists. For any other power: base log * exponent = 10^x. Example, 3²: 3 log * 2 = 10^x gives 9. To enter 5×10⁶ use 6 10^x * 5 =.
How it shows numbers
Whole numbers end with a point (14.). It fits 12 digits; longer results are shown in full. Very small ones look like 6.666666666 -8 (that is 6.67×10⁻⁸, with the last digit cut off, not rounded). 1000 e^x gives Error because it is too large.
Catalogue checked against the official demo: 597 key sequences compared with it, looking at the screen after every key. See the method and the full table. If you find another quirk, write to us.
Why practise with the calculator before the exam
Official pilot theory exams in Spain (PPL, CPL, ATPL, IR and ratings) are taken on a computer at SENASA on behalf of AESA. Inside the exam application you get an on-screen scientific calculator, and it is the one you will use: SENASA presents it as the support tool for calculations, and the exam-room rules are in its theory exam guide (in Spanish). Always check the current version.
In subjects such as General Navigation, Performance, Mass and Balance or Flight Planning, a good share of the time goes on typing. If you know by heart where every button is and how the calculator reacts, you make fewer mistakes and have time left to review.
It respects the priority of multiplication and division over addition and subtraction: 2 + 3 * 4 = gives 14. Even so, in long chains use parentheses (see the quirks above).
Memory:MS stores the number on the screen, MR recalls it, M+ and M- add to or subtract from what is stored, and MC clears it. The C button does not clear the memory.
«Error» appears when you divide by zero, take the root of a negative number or ask for the asin or acos of a number greater than 1.
The order of the keys, the trick to correct a mistyped number, how long numbers are shown and what «NaN.00000NaN» means are explained, each with its demo, in the quirks above.
A tip for studying at night
The site comes in dark mode so that it is easy on the eyes. While you are learning, keep the «Study helper» on: under the calculator you will see your formula exactly as the calculator understood it, and it will warn you if you press keys in an order that does not work, if it recognises a unit conversion (so that you can check it goes the right way) or if the real calculator is giving you a wrong result.
Exam mode: put yourself in exam-day shoes
When the exam is a few days away, switch on «Exam mode». The calculator takes its real size and colours, the formula, the warnings and every other aid disappear, and it can only be used with the mouse. It is exactly what you will find at SENASA: if it goes well here, it will go well there.
Units and abbreviations you will be typing
ATPL, CPL and IR exams in Spain are in English only, and the PPL can be taken in Spanish or English (AESA Resolution of 28 July 2025, sections 10.1 and 10.2, in Spanish). These are the units and abbreviations that come up most, with a useful equivalence for each. The study helper uses the same abbreviations.
The decimal separator is a point (1.852), in the exam and on the calculator. Factors are rounded the way they usually appear in questions; always use the ones your question gives you.
Frequently asked questions
Which calculator is used in the SENASA exams?
SENASA's own scientific calculator, shown on the exam computer screen; no other calculator may be used. SENASA publishes a demo version on its website and PilotKeys reproduces its behaviour key by key, adding dark mode, study aids and an exam mode with the real look.
Is it valid for PPL, CPL, ATPL and IR exams?
Yes. It is the calculator SENASA provides as a support tool for the pilot theory exams it runs on behalf of AESA, so it applies to any of those licences and ratings.
How do I enter a sine or cosine on the SENASA calculator?
Type the angle in degrees first and press the function second: 30 then sin gives 0.5. If you press sin before the number, it is applied to the 0 on the screen and the result is useless. The worked examples page has full formulas key by key.
Does it work on a phone?
Yes, the whole calculator fits on a phone screen. Even so, since the exam is done with a computer mouse, it is worth practising that way too, especially with exam mode on.
Can I bring my own calculator to the SENASA exam?
The exam calculation tool is the scientific calculator shown on the exam computer, which is why it pays to practise with it beforehand. What may or may not be taken into the room is set out in the SENASA theory exam guide (in Spanish): always check the current version.
Does the exam calculator work in degrees or radians?
Degrees. sin, cos and tan expect the angle in degrees, and asin, acos and atan return degrees. The result of these functions is also rounded to 4 decimals.
Can I use the keyboard with the exam calculator?
The official demo calculator only responds to mouse clicks: it has no keyboard shortcuts (we checked its code). In this replica the keyboard is off by default so that you train as in the exam, but you can turn it on.
Why does 1 + sin 30 give 10.5 instead of 1.5?
It is a quirk of the official calculator: when the result of a trig function is the second number in an addition, it glues it on instead of adding it. To avoid it, start with the trig function (30 sin + 1) or multiply the result by 1.
Is this an official SENASA or AESA website?
No. It is an independent, free study tool with no connection to SENASA or AESA. It reproduces the behaviour of the official calculator so that you can practise.
In which language are the exams in Spain?
ATPL, CPL, MPL, IR and BIR theory exams are in English only; PPL and LAPL exams can be taken in Spanish or English, under the AESA Resolution of 28 July 2025 (BOE, sections 10.1 and 10.2). The calculator itself has no language: its buttons are the same in both.
How much does it cost and what data does it keep?
It is free and needs no sign-up. Your calculations never leave your device.
What we say about how the calculator works comes from our comparison with the official demo. Everything else comes from these sources; if anything changes, what they say prevails.