fx-991ES PLUS calculator online
A free scientific calculator in your browser that works like the fx-991ES PLUS: same key layout, SHIFT functions, fraction answers and degree or radian mode. No download, no sign-up.
fx-991ES style scientific calculator
Click the keys or use your keyboard (numbers, + − * / ^ ( ), Enter, Backspace, Esc). Everything runs in your browser.
How to use the online calculator
- Click the keys or type on your keyboard: numbers, + − * / ^ ( ), Enter for =, Backspace for DEL and Esc for AC.
- Press SHIFT first to use the yellow function above a key — for example SHIFT + sin gives sin⁻¹, SHIFT + x² gives x³.
- Missing closing brackets are added for you, just like on the real calculator: √(16 = 4.
- After =, pressing an operator carries on from the answer (Ans). Pressing a number starts a new calculation.
What each key does
| Key | Function | With SHIFT |
|---|---|---|
| S⇔D | Switch the answer between a fraction and a decimal | — |
| DRG | Cycle the angle unit: Degrees (D), Radians (R), Gradians (G) | — |
| x⁻¹ | Reciprocal | x! (factorial) |
| nCr | Combinations, e.g. 5C2 = 10 | nPr (permutations) |
| √ | Square root | ∛ cube root |
| x² | Square | x³ cube |
| xʸ | Power, e.g. 2^(10) = 1024 | — |
| log / ln | Base-10 and natural logarithm | 10ˣ / eˣ |
| sin / cos / tan | Trigonometry in the current angle unit | sin⁻¹ / cos⁻¹ / tan⁻¹ |
| ×10ˣ | Scientific notation: 1.5 ×10ˣ 3 = 1500 | — |
| M+ / MR | Add the answer to memory / recall memory | M− / MC (clear memory) |
| Ans | The last answer | — |
Fractions and the S⇔D key
Like the fx-991ES PLUS, answers that are exact fractions are shown as fractions first. 1 ÷ 3 + 1 ÷ 6 shows 1⁄2; press S⇔D to see 0.5, and press it again to switch back. Irrational answers such as √2 or π are always shown as decimals to 10 significant digits.
Degrees vs radians
The calculator starts in degree mode (D on the screen), which is what most school trigonometry uses: sin(30) = 0.5. If you get strange trig answers, check the mode — in radian mode sin(30) is −0.988. Press DRG to cycle between degrees, radians and gradians.
Worked examples
| Problem | Keys | Answer |
|---|---|---|
| Hypotenuse of a 3–4 triangle | √( 3 x² + 4 x² = | 5 |
| Angle with sin θ = 0.5 | SHIFT sin 0.5 = | 30 |
| Ways to choose 5 cards from 52 | 52 nCr 5 = | 2598960 |
| Compound interest: 1000 at 5% for 10 years | 1000 × 1.05 xʸ 10 = | 1628.894627 |
| log of 0.001 | log 0.001 = | −3 |
Differences from the real fx-991ES PLUS
This page is an independent scientific calculator made by HintLoot. It is not affiliated with Casio, and it does not copy the calculator's software. It covers the everyday COMP-mode functions students use most. The real fx-991ES PLUS also has equation solving (EQN), statistics (STAT), matrix, vector, complex number and base-n modes, plus integration and differentiation, which are not included here yet.
If your exam allows a calculator, you will still need the physical one on the day — use this page for homework, practice and quick checks.