Scientific Calculator Guide: 10 Functions Everyone Should Know

Scientific calculators look intimidating, but most of those buttons exist for niche use cases. The ten functions below cover everything most students, engineers and curious adults will ever need. Learn what each one does and your calculator stops being a black box.

1. Order of operations (PEMDAS / BODMAS)

Before pressing any button, understand the order your calculator will follow:

• P/B — Parentheses / Brackets first
• E/O — Exponents / Orders (powers, roots)
• MD — Multiplication & Division (left to right)
• AS — Addition & Subtraction (left to right)

Modern scientific calculators do this for you automatically. 2 + 3 × 4 = 14, not 20. If you want 20, type (2 + 3) × 4.

2. The Equals key (and how to chain)

Hit = at any time to see the running result. Most scientific calculators let you continue from the previous answer with the Ans key — useful for multi-step problems without retyping.

3. Exponents (x^y or ^)

2^10 = 1,024. 10^6 = 1,000,000. For very small numbers, 2^−3 = 0.125.

Use this for compound interest, scientific notation, computer-science problems, exponential growth.

4. Square root and other roots

√25 = 5. For other roots, use the ˣ√y button or the equivalent ^(1/n):

• Cube root of 27 = 27^(1/3) = 3
• 5th root of 32 = 32^(1/5) = 2

5. Logarithms (log and ln)

Logs answer: "to what power must I raise the base to get this number?"

• log(1000) = 3 because 10^3 = 1000 (base 10)
• ln(e) = 1 because e^1 = e (natural log, base ≈ 2.718)

Used in earthquake magnitudes, pH, decibels, half-lives.

6. Trigonometry: sin, cos, tan

Used everywhere from physics to architecture to game design. Three things to know:

• sin = opposite ÷ hypotenuse
• cos = adjacent ÷ hypotenuse
• tan = opposite ÷ adjacent

Make sure the angle mode is right: DEG for everyday geometry, RAD for physics and engineering. If sin(90) gives you 0.893 instead of 1, you are in RAD mode.

7. Inverse trig (sin⁻¹, cos⁻¹, tan⁻¹)

Given a ratio, find the angle. sin⁻¹(0.5) = 30° in DEG mode. Useful for ramp angles, surveying, navigation.

8. Memory functions (M+, M−, MR, MC)

• M+ — add the current value to memory
• M− — subtract
• MR — recall the stored value
• MC — clear memory

Practical use: keep a running subtotal while computing intermediate values. Saves writing things down.

9. Pi (π) and Euler's number (e)

π ≈ 3.14159 — for any circle math. Area = π × r², circumference = 2 × π × r.

e ≈ 2.71828 — for compound interest, exponential decay, statistics.

10. Scientific notation (EXP or EE)

For huge or tiny numbers. 6.02 × 10²³ (Avogadro) is typed 6.02 EXP 23. 1.6 × 10⁻¹⁹ (electron charge) is typed 1.6 EXP −19.

A worked example pulling several together

Find the hypotenuse of a right triangle with sides 3 and 4.

c = √(3² + 4²) = √25 = 5. Keystrokes: 3 x² + 4 x² = √Ans = 5.

Find the angle opposite the side of length 3: sin⁻¹(3/5) = 36.87° in DEG mode.

Common mistakes

• Mode confusion. RAD vs DEG is the #1 source of wrong trig answers.
• Implicit multiplication. "sin30" might mean sin(30) on one calculator and sin × 30 on another. Always parenthesise.
• Forgetting parentheses around fractions. 1 / 2 × 4 = 2, not 0.125. You want 1 / (2 × 4).
• Rounding too early. Keep full precision until the final step.

Frequently asked questions

Are there free scientific calculators online? Yes — including the one on this site, which mirrors the layout of a Casio fx-991.

Do I need a graphing calculator? Only for serious calculus, statistics or programming coursework.

Which mode should I use? DEG for everyday geometry and trigonometry; RAD for physics, engineering and calculus.

Try our Scientific Calculator — all ten functions on a single, mobile-friendly keyboard.