A scientific calculator that shows its working
Every key of the fx-991ES PLUS, in the same place, with the answer appearing as you type. It is built for Cambridge O Level, IGCSE and A Level maths and sciences.
Natural display
Fractions stack, roots stretch and powers rise, the way you write them. Move into any box with the arrows or by tapping.
Exact answers and insights
See √3/2, 5π/6 or 7/12, then the decimal, recurring decimal, prime factors or binary in one tap.
Solve, integrate, differentiate
SOLVE finds every real root. ∫, d/dx and Σ use the textbook layout, with answers to ten significant figures.
Every Casio mode
Equations, statistics with regression, normal, binomial and Poisson distributions, tables, matrices, vectors and Base-N.
Formula shelf
Physics and chemistry formulas for O Level, IGCSE and A Level. Enter what you know with units and get the missing quantity, with the working.
Constants and conversions
The 40 scientific constants with CODATA values, and conversions between more than 100 units.
Straight to a graph
Equation mode opens your equation in the graphing calculator, as a graph or as a table of values.
Phone, tablet and keyboard
Full screen on any device. On a computer, type straight in: / for a fraction, ^ for a power, Enter for equals.
Questions
- Is this the same as a Casio fx-991ES PLUS?
- The keys are laid out the same way and follow the same order of operations, so what you practise here carries over to your own calculator. It adds things a small screen cannot: a live answer while you type, a history you can tap, undo, and all the modes on one screen.
- Why does 1÷2π give 0.159 and not 1.571?
- Like the fx-991ES PLUS, multiplication without a sign (2π, 3A) is done before ÷. Use the fraction key, or brackets, when you mean something else.
- Can it give exact answers like √3/2 and 5π/6?
- Yes. Answers that are fractions, surds or multiples of π are shown exactly, and S⇔D switches to the decimal. Turn exact answers off in Setup if you prefer decimals.
- Does it solve equations?
- Type an equation with = (ALPHA CALC) and press SOLVE, or press = on it. Unlike the real calculator it lists every real solution it finds, not only the one nearest your starting value. Equation mode solves simultaneous equations, polynomials up to degree 4 and polynomial inequalities.
- Can it do physics and chemistry formulas?
- Yes. Open the Formula shelf, choose a formula such as v = u + at or pV = nRT, pick the quantity you want, and enter the others with their units. It converts units like °C, cm³ and kPa, and shows the rearranged formula and the working.
- Can I use this in an exam?
- No. It is a study tool for revision and homework. Cambridge exams need a physical, approved calculator.