Is the online calculator free? +
Yes. Every calculator on GratisRekenmachine is completely free to use, with no account, no registration and no trial period.
Does the calculator work without installing anything? +
Yes. Everything runs directly in your browser on desktop, tablet and phone. There is nothing to download and no plug-ins are required.
Can I use the calculator with my keyboard? +
Yes. Use the number keys and + − * / for the operations, Enter for the result, Backspace to delete a character and Escape to clear. You can also click into the middle of a calculation and edit it.
Why does this calculator give 6 for 2 + 2 × 2 while another gives 8? +
Because multiplication comes before addition. First 2 × 2 = 4, then 2 + 4 = 6. Calculators showing 8 work strictly left to right and ignore the order of operations. Mathematically, 6 is the correct answer.
Does my calculation stay private? +
Yes. The calculation happens entirely on your own device. What you enter is not sent to a server and is not stored.
How do you calculate VAT on a calculator? +
To add VAT, multiply the amount excluding VAT by 1.21 (at 21%) or 1.09 (at 9%). To remove VAT, divide the amount including VAT by 1.21 or 1.09. Never simply subtract 21% from the gross amount — that gives too low an answer.
How do you calculate percentages on a calculator? +
To calculate X% of Y, divide X by 100 and multiply by Y. So 25% of 200 becomes 0.25 × 200 = 50. To find what percentage X is of Y, divide X by Y and multiply by 100.
How do you work out a discount on a calculator? +
Multiply the price by the percentage you pay, not by the discount. At 30% off you pay 70%, so € 80 × 0.70 = € 56. If you want the discount amount itself, calculate € 80 × 0.30 = € 24.
How do you enter a fraction on a calculator? +
A fraction is a division: enter 3/4 as 3 ÷ 4, which gives 0.75. To keep working with fractions rather than decimals, put parentheses around each one, for example (3÷4) + (1÷2). On physical calculators you normally use a dedicated fraction key, often labelled a b/c.
How do you raise to a power on a calculator? +
Use the caret: 2^10 means 2 to the power of 10 and gives 1024. In scientific mode above this is the xʸ key. Note that exponentiation is right-associative: 2^3^2 reads as 2^(3^2) = 512, not (2^3)^2 = 64.
How do you square a number on a calculator? +
Squaring is multiplying a number by itself. Use the x² key in scientific mode, or type ^2 after the number. Mind the difference between −2² and (−2)²: the first is −4, the second is 4.
How do you calculate a square root on a calculator? +
Use the √ key in scientific mode or type sqrt( followed by the number. sqrt(16) gives 4. Do not forget the closing parenthesis if you continue calculating, for example sqrt(16)+2.
How do you calculate a cube root on a calculator? +
A cube root is a power with exponent 1/3. So type 27^(1÷3), which gives 3. For an nth root, use ^(1÷n) in the same way.
How do you calculate a square root without a calculator? +
Estimate between two squares you know. For √50 you know 7² = 49 and 8² = 64, so the answer sits just above 7. Refine with Newton’s method: divide 50 by your estimate and average the two. 50 ÷ 7 ≈ 7.14, averaged with 7 gives 7.07 — correct to two decimals.
Where is pi on your calculator? +
In scientific mode above, π has its own key; you can also simply type pi. On physical calculators π is usually a second function above a key, reached with SHIFT or 2nd. The value is approximately 3.14159265.
How do you calculate a logarithm on a calculator? +
Use log( for base-10 logarithms and ln( for the natural logarithm with base e. log(1000) gives 3 and ln(e) gives 1. For another base, divide: log base 2 of 8 is ln(8) ÷ ln(2) = 3.
How do you use tan on your calculator? +
Type tan( followed by the angle and close the parenthesis. First check whether your calculator is in degrees or radians, because that changes the answer entirely. tan(45) is 1 in degrees but roughly 1.62 in radians.
How do you use scientific notation on a calculator? +
Scientific notation is a number times a power of ten. Enter 3.2 × 10⁵ as 3.2×10^5. On physical calculators you normally use the EXP, EE or ×10ˣ key for this.
How do you set your calculator to degrees? +
In scientific mode above, use the Degrees/Radians switch. The result is recalculated immediately. On physical calculators you normally use the MODE or SETUP key and choose DEG; a small D or DEG indicator then appears on the display.
What is a graphing calculator? +
A graphing calculator draws functions as a graph instead of only giving a number. That lets you see at a glance where a function crosses the x-axis, where its vertex lies and how the curve behaves. You can do this free online here with the graphing calculator.
How do you put a graphing calculator into exam mode? +
This differs per brand and model. On many Casio models you hold a key combination while switching on; on Texas Instruments it goes through a menu or by linking two calculators. A flashing light or an on-screen notice indicates the mode is active. Always consult the manual for your specific model and your school’s instructions, because an incorrectly configured calculator can be refused at the exam.
How do you take a graphing calculator out of exam mode? +
Usually via a reset or by connecting the calculator with a cable to another calculator or a computer. On some models the mode expires by itself after a number of hours. Again, your model’s manual is authoritative, because the steps differ per manufacturer.
Which calculator do you need for secondary school? +
In the lower years a simple or scientific calculator is almost always sufficient. From the upper years, havo and vwo maths usually prescribe a graphing calculator. Your school publishes a list of permitted models each year; follow that list, as only those calculators are allowed in the exam.
Which calculator do you need for vwo? +
For maths A, B and C at vwo level a graphing calculator is almost always required. Exactly which models are permitted is set annually and communicated by your school. For physics and chemistry a scientific calculator is often sufficient.
How do you calculate a factorial on a calculator? +
A factorial means multiplying all whole numbers up to that number: 5! = 5 × 4 × 3 × 2 × 1 = 120. In scientific mode above, use the n! key. On physical calculators the factorial is usually a second function, reached with SHIFT.
How do you reset a Casio calculator? +
On most Casio fx models you reach the clear menu via SHIFT then 9 (CLR), where you choose between settings, memory or all. If the calculator misbehaves, there is also a small reset button on the back. Afterwards, check that the angle mode is back on degrees.
How do you calculate your BMI with a calculator? +
Divide your weight in kilograms by the square of your height in metres. At 70 kg and 1.75 m you calculate 70 ÷ (1.75 × 1.75) ≈ 22.9. So convert your height from centimetres to metres first, as that is the most common mistake.
Does the calculator work well on mobile? +
Yes. The keys are large enough for thumb use and the page adapts to your screen size. The graphing calculator works with touch too: drag to pan the graph.