I Built the Scientific Calculator
I Wish I Had in Engineering School

I've been there. Usually it's one of three things: (1) You're in degree mode when you need radians (or vice versa)—this is the #1 mistake, (2) You forgot parentheses and order of operations is messing things up, or (3) The expression is invalid somehow. Try clearing (AC) and starting fresh. Pro tip: Always check your mode first!

Great question. ln is the natural log (base e ≈ 2.718) and log is base-10. ln shows up in calculus, physics, anything continuous—population growth, radioactive decay, that kind of thing. log is for human-scale stuff like pH, decibels, Richter scale. If you're not sure which to use, check your textbook or problem statement—it'll tell you. I remember it like this: 'ln is for nature (e), log is for humans (10).'

Here's how I do it: Calculate a number I want to save → press M+ (stores it in memory) → do other calculations → press MR (brings back the saved number). When I'm done, I hit MC to clear memory. That's it. M- subtracts from memory, which I rarely use but it's there. Real example: I was calculating compound interest. I stored the interest rate in memory, calculated each year's growth, and recalled the rate whenever I needed it. Saved me so much time.

My rule: If you can measure it with a protractor (real-world angles), use degrees. If you're doing calculus, derivatives, or pure math, use radians. Most physics problems use radians too. Here's the thing: In calculus, derivatives of trig functions ONLY work in radians. d/dx(sin(x)) = cos(x) only if x is in radians. Trust me, I learned this the hard way on an exam. When in doubt, check what mode your homework or textbook is using.

This calculator follows PEMDAS (Parentheses, Exponents, Multiplication/Division, Addition/Subtraction). I always use parentheses when I'm unsure—it's clearer and prevents mistakes. For example, instead of typing 8/2*2, I'll type 8/(2*2) to be explicit. Fun fact: Multiplication and division are equal priority, done left to right. Same with addition and subtraction. So 8-4+2 = (8-4)+2 = 6, not 8-(4+2) = 2. When in doubt, add parentheses.

You bet! I love this feature. Just type numbers and operators directly. Enter calculates, Escape clears all, Backspace deletes last character. It feels just like using a real calculator but faster. Try it—it's way faster once you get the hang of it. I personally use keyboard for numbers and basic operations, then click the function buttons (sin, cos, log) with my mouse. Best of both worlds.

Usually means the expression is invalid. Common causes: Division by zero (5/0), square root of negative number (√(-4)), malformed expression (missing operators), or unbalanced parentheses. I double-check my parentheses first—that's usually the culprit. If I'm doing trig, I make sure I'm in the right mode (DEG vs RAD). Try hitting AC to clear and starting fresh. Still stuck? Break your expression into smaller parts to find where it's breaking.

It uses double-precision floating-point math, which means about 15-17 significant digits. For 99.9% of calculations you'll ever do, this is more than enough. I've used it for engineering work, physics problems, and financial calculations without issues. For context: most physical constants are only known to 4-6 significant digits anyway. The only time you'd need more precision is advanced scientific research or certain math proofs. For everything else? You're covered.

Ah, one of my favorites! It recalls your last answer. Perfect for multi-step problems. For example, if I just calculated sin(30) and got 0.5, I can hit Ans to use 0.5 in my next calculation. Saves so much typing and reduces errors. Real example: Calculate circumference of circle with radius 5: 2 × π × 5 = 31.415. Now calculate area: π × Ans² = π × 31.415². Boom, done. No retyping, no mistakes from copying numbers wrong.

Yes! Use the ! button. I use this for probability and combinatorics. 5! = 5×4×3×2×1 = 120. Fair warning: factorials get huge fast. 10! = 3,628,800. 100! has 158 digits. This calculator handles it, but... wow. Practical example: How many ways to arrange 5 books on a shelf? 5! = 120 ways. How many possible poker hands? 52! / (5! × 47!) — use combinations for that one.

Easy! Use √x for square root and ³√x for cube root. For example: √25 = 5 (square root of 25) and ³√27 = 3 (cube root of 27). Need a different root? Use y√x (nth root). For the 4th root of 16: type 16 y√x 4 = 2. Mathematically, this is 16^(1/4). I use these all the time for finding dimensions from areas or volumes. If a square has area 64, each side is √64 = 8.

Scientific notation is a way to write really big or really small numbers. Like 5.97 × 10²⁴ instead of 5,970,000,000,000,000,000,000,000. Use the EXP button to enter it. For 5.97E24: type 5.97 EXP 24. This is essential for physics and chemistry (mass of Earth, Avogadro's number, etc.). I also use it for engineering—millions, billions, whatever. Way faster than counting zeros!

For homework? Absolutely, that's what I built it for. For exams? It depends. Some online exams allow calculators, some don't. Always ask your instructor first. That said, this is great for practicing and checking your work. I used to solve problems twice—once with a calculator, once by hand—to make sure I understood. This calculator is perfect for that approach. Learn the concept, verify with the calculator.

Graphing calculators (like TI-84) can plot functions, solve equations simultaneously, and have advanced statistical features. This scientific calculator focuses on numerical calculations—trig, logs, powers, roots. It won't graph y = x², but it'll calculate 5² + 3² = 34 instantly. For most high school and early college math? You probably don't need graphing. For calculus, linear algebra, or advanced stats? You might want a graphing calculator.

Hyperbolic functions (sinh, cosh, tanh) are like trig functions but for hyperbolas instead of circles. They show up in advanced engineering—suspension cables (catenary curves), relativity, certain differential equations. This calculator doesn't have dedicated hyperbolic buttons, but you can calculate them: sinh(x) = (eˣ - e⁻ˣ)/2. Honestly? Most people won't need these unless you're in upper-division engineering or physics. I included the formula for the 2% who do!

For percentages: Use the % button. It divides by 100. So 50% = 50/100 = 0.5. For calculations: 200 + 10% = 200 + (200 × 0.10) = 220. For fractions, you can use division: 1/2 = 0.5, 3/4 = 0.75. This calculator gives decimal answers, not fraction notation. If you need fraction answers (like 3/4 instead of 0.75), you'll want a different calculator or convert manually.

The history shows your last 10 calculations, and you can click any to reuse it. But there's no permanent save feature—refreshing the page clears everything. I built it this way intentionally: your privacy matters, and I don't want to store your data on my servers. If you need to save work, I recommend screenshotting or copying to a document. Quick tip: Click any history item to instantly reuse that result.

Basic calculators do: +, -, ×, ÷, maybe % and √. Scientific calculators (like this) add: trigonometry (sin, cos, tan), logarithms (ln, log), powers (x², x³), roots (√x, ³√x), exponents (eˣ, 10ˣ), factorials (!), constants (π, e), memory functions (M+, M-, MR), and scientific notation (EXP). If you're in algebra or below, basic is fine. Geometry? You'll need trig. Pre-calc and above? Definitely scientific.

The history shows your last 10 calculations with both the expression and result. I use this constantly for multi-step problems. Click any history item to instantly insert that result into your current expression. Example: Calculate area of circle (π × r²), get 78.54. Now calculate volume of cylinder with that area as base: 78.54 × height. Click the history item, type × 10, done! Also great for checking your work—scroll through to see what you calculated.

100% yes. Everything happens right here in your browser—your numbers never go to my servers. I don't track what you calculate, I don't store your history, I don't even use analytics on the calculator itself. I take privacy seriously. Refresh the page and everything's gone. This is how all calculators should work: do the math, forget the data. Your calculations are yours alone.