IGCSE Maths Calculator Skills: Watch Every Key Press

For IGCSE Maths you need six calculator skills more than any others: standard form and rounding, switching between fractions and decimals, degree mode for trigonometry, solving equations, the mean from a frequency table, and tables of values for graphs. Our calculator skills guides cover each one for the Casio ClassWiz, and four of them now have a walkthrough that lights up every key you press on the fx-991EX.

How the walkthroughs work

Open a guide, choose the fx-991EX tab, and press Watch the key presses. A drawing of the calculator lights each key as it is pressed, with the screen after each press and one line of explanation per step. Pause, step back, step forward or slow it down; nothing plays until you open it.

The key presses follow the guide's numbered steps, and the last screen shows the guide's worked-example answer, so you can copy it on your own calculator and check. The fx-991CW has written steps on every guide but no walkthrough yet.

The six skills

1. Standard form and rounding

Use the ×10ˣ key for powers of ten, and write the answer as $1.44 \times 10^4$, never as the calculator's 1.44E4.

Keep the full value (Ans, or a stored letter) and round only the final answer. Zeros at the start of a number are not significant: $0.00456782$ to 3 s.f. is $0.00457$. Switch Sci or Fix off afterwards, or the next question shows rounded values. Standard form and rounding guide.

2. Fractions and decimals

On the fx-991EX, press S⇔D after an answer to switch between the fraction and the decimal; on the fx-991CW use FORMAT. If a question asks for a fraction or an exact answer, give the fraction. Fractions and decimals guide.

3. Degree mode for trigonometry

IGCSE trigonometry is in degrees. On the fx-991EX: SHIFT MENU (SETUP), 2 (Angle Unit), 1 (Degree). Check the indicator at the top of the screen before any sine rule, cosine rule or bearings question: an answer in radian mode is wrong even when every step is right. Degrees or radians guide.

4. Solving equations

fx-991EX: MENU, Equation/Func, then Polynomial for a quadratic or Simul Equation for a pair of simultaneous equations.

This is for checking. If a question asks you to solve by factorising, by the formula or "show your working", the calculator's answer alone is not enough. Type every coefficient, $0$ for a missing term, and use the negative key, not subtract. Solving equations guide.

5. The mean from a frequency table

Turn on the frequency column first: SHIFT MENU (SETUP), ▼, Statistics, Frequency?, On. Then MENU 6, 1-Variable, type the values and the frequencies, and OPTN, 1-Variable Calc.

Forgetting the frequency column treats the table as a short list of single values. For grouped data, type the midpoints, not the class boundaries, and say the mean is an estimate. Statistics guide.

6. Tables of values for graphs

The table function fills in "complete the table" questions in seconds. Check one value by hand with brackets, since typing $-1^2$ gives $-1$, and join the plotted points with a smooth curve, not straight lines. Tables of values guide.

Exam rules: which papers, which calculator

Edexcel International GCSE 4MA1: a calculator is allowed in every paper (1F, 2F, 1H, 2H). Calculators with databanks, retrieval of text or formulae, QWERTY keyboards, or built-in symbolic algebra, differentiation or integration are banned.
Cambridge IGCSE 0580: Papers 1 and 2 are non-calculator. Papers 3 and 4 need a scientific calculator. The Cambridge Handbook does not allow a graphic display unless the syllabus says otherwise, so a graphic calculator is not one for 0580. It also says to clear any information and programs from the memory before and after the exam.

The fx-991EX and fx-991CW have no exam mode: they have no CAS and no wireless link, so the rule is to clear what is stored. On the fx-991EX: SHIFT 9 (RESET), Initialize All, Yes. On the fx-991CW: SETTINGS, Reset, Initialize All, Yes. Before taking a graphic calculator into a 4MA1 exam, check with your exams officer. More on the which calculators are allowed guide and the reset guide.

Cambridge students: half your papers have no calculator, so practise the non-calculator methods too.

One skill a day

Watch a walkthrough once, then do the worked example on your own calculator with the walkthrough closed, and check your answer against the guide.

Practise this topic

FAQ

Is a calculator allowed in IGCSE 0580 Paper 2?

No. Cambridge 0580 Papers 1 and 2 do not allow a calculator. Papers 3 and 4 need a scientific calculator.

Is a calculator allowed in Edexcel 4MA1?

Yes, in every paper (1F, 2F, 1H and 2H). The specification bans calculators with databanks, retrieval of text or formulae, QWERTY keyboards, or built-in symbolic algebra, differentiation or integration.

Can I use a graphic calculator in Cambridge IGCSE Maths?

Not in 0580. The Cambridge Handbook does not allow a graphic display unless the syllabus says otherwise, and the 0580 syllabus asks for a scientific calculator.

Every guide has the steps for the Casio fx-991EX and fx-991CW, with a worked example to check your answer.

Open the calculator skills guides →