Mental arithmetic sounds harmless at first. Until you realize that the problems on the DLR test are presented exclusively through audio—no paper, no pen, no aids—and that you have to type in the answer immediately while the next problem is already playing. Anyone unfamiliar with this format is at a disadvantage on test day simply because of that. Those who practice it quickly realize that KRN is one of the modules where preparation has the most directly measurable impact.
What is the KRN test?
KRN stands for mental arithmetic and is one of the ten modules of the DLR Cockpit Certificate. The module tests the ability to solve mathematical problems quickly and correctly in your head—under realistic conditions: under time pressure, without aids, and in an audio format that many candidates are not used to.
The rationale is sound: Pilots must regularly perform quick mental calculations in the cockpit—fuel consumption, time calculations, course deviations. Relying on external aids during these tasks wastes time. The KRN test assesses precisely this mental speed and accuracy.
Format and Procedure
The following is known about the KRN format from consistent candidate reports:
- The tasks are presented audibly —you hear them, you don’t see them on the screen
- You type the result directly using the keyboard
- No pen, no paper, no calculator —no aids allowed
- The tasks vary in complexity: simple addition and subtraction, but also multi-step calculations involving parentheses, multiplication, and division
- The pace is fast —there is little time between entering an answer and the next problem
The crucial detail: You hear the problem once. There is no repetition. Anyone who gets distracted or doesn’t process the number immediately loses precious seconds.
What the test really measures
KRN is not purely a math test. What is measured is the combination of:
- Auditory processing speed: How quickly can you process and mentally retain the numbers you hear?
- Mental arithmetic under time pressure: Not just whether you can do math, but how fast
- Resilience to errors: Can you let go of a wrong answer and immediately focus on the next task—without letting the mistake throw you off?
This means: Just because you were good at math in school doesn’t automatically mean you’ll do well on the KRN. And those who have adapted to the specific format through consistent practice will perform well even if math isn’t their strongest subject.
The most common mistakes on the KRN
1. Practicing the wrong format
Those who prepare for KRN with pencil-and-paper problems or a standard math app are practicing arithmetic—but not what is actually tested. The audio format, keyboard input, and time pressure must be practiced separately. Being unfamiliar with the format on test day costs points that have nothing to do with knowledge.
2. Being too slow with basic arithmetic
If you still have to pause to think about simple problems like “17 × 4” or “144 ÷ 12,” you’ll fall behind in terms of speed. Basic arithmetic—especially multiplication tables up to 20 and simple division—should be second nature.
3. Unable to move past mistakes
Mistakes happen. What matters is how quickly you can get back on track. Candidates who “get stuck” briefly after a mistake often miss the next problem almost entirely. Resilience in the face of your own mistakes is just as important in the KRN as mathematical accuracy.
4. No approximation strategy
For more complex problems, it’s worth making a rough estimate first and then refining it—instead of calculating linearly from left to right and ending up in a dead end. Without an approximation strategy, difficult problems will take significantly longer to solve.
Specific training tips for KRN
Tip 1: Master the multiplication tables up to 20
Before you start format-specific training, make sure you can fluently recall all multiplications from 1 × 1 to 20 × 20. That sounds trivial—but it isn’t. Test yourself: How long does it take you to calculate “17 × 18”? If you have to think for more than 3–4 seconds, it’s worth spending a few days doing targeted multiplication drills.
Tip 2: 10–15 minutes of mental arithmetic daily—even without an app
The best complementary exercise for format training is integrating mental arithmetic into your daily routine: adding up prices at the supermarket, subtracting times, calculating percentages while reading. It sounds trivial, but it has a real effect on recall speed.
Tip 3: Practice estimation
Practice estimating results first, then refining them. Example: “384 ÷ 16” — first roughly: “400 ÷ 16 ≈ 25,” then correct: 384 ÷ 16 = 24. This is faster than exact sequential calculation and is especially helpful for multi-step problems.
Tip 4: Practice error tolerance
Consciously create situations where you answer a question incorrectly—and practice moving on immediately without pausing. This may sound counterintuitive, but it’s an important skill for test day.
Tip 5: Practice under time pressure, not just for accuracy
Many test-takers first focus on accuracy and then turn their attention to speed. Better: practice under mild time pressure from the start. The combination of accuracy and speed must be developed simultaneously.
How to integrate KRN into your preparation
KRN belongs in every practice session—but not as the main focus. The recommended breakdown:
- 10–15 minutes of KRN-specific practicedaily, preferably at the start of the session when your concentration is still fresh
- Additionally in daily life: Incorporate mental arithmetic into everyday situations
- In the last 2 weeks before the test: Increase the pace, shorten breaks between tasks
On DLR-TEST.TRAINING, you can practice KRN in its authentic format—audio tasks, keyboard input, time pressure. The adaptive stage system ensures that the difficulty increases as you progress: You’ll never be bored by tasks that are too easy or frustrated by tasks that are too hard.
Go directly to KRN training: app.dlr-test.training → KRN
Train for KRN now
Authentic format, adaptive difficulty system, detailed evaluation after each run.
Frequently asked questions about the KRN test
Can I take notes during the KRN test?
No. No aids of any kind are allowed—no pen, no paper, no calculator. The problems are presented audibly, and you enter the answer directly using the keyboard. That’s exactly why it’s so important to practice the format beforehand.
How complex are the KRN problems?
The problems range from simple addition and subtraction to multi-step calculations involving parentheses and mixed operations. The difficulty increases as the test progresses. With a good grasp of estimation strategies and automated basic arithmetic, this is quite manageable.
I’m not good at math—should I still aim to become a pilot?
Yes. The KRN doesn’t test advanced mathematics, but rather mental arithmetic under time pressure. This is something that can be trained—regardless of what your math grades were in school. If you practice regularly, you’ll see the difference.