A Free Online Scientific Calculator Laid Out Like the Casio fx-83GTX: How to Practise for GCSE

On a GCSE calculator paper, time goes in two places students do not expect. Hunting for a key they rarely use, and fixing an answer that came out as a fraction or a surd when the question wanted a decimal.

Both are practice problems, not maths problems. So we built a free online scientific calculator laid out key for key like the Casio fx-83GTX and fx-85GTX, the calculators most students take into their exams. The buttons your child learns on it are the buttons in the exam hall.

Why the layout matters

Many online calculators put every function on its own button. A real exam calculator does not. Many keys do three jobs, one printed on the key, a gold one you reach with SHIFT and a pink one you reach with ALPHA. A student who has only practised on a phone app has never had to find those.

Our calculator copies that exactly, with the same gold and pink labels in the same places, the same SETUP menu with the same numbers, and answers that come out in the same form. Practising on it means the real calculator feels familiar on the day.

The three keys to learn first

SHIFT. Press SHIFT, then a key, to get the gold function printed above it. The inverse trig functions, sin⁻¹, cos⁻¹ and tan⁻¹, live here, and students who cannot find them lose easy marks on missing angle questions.

ALPHA. Press ALPHA, then a key, to get the pink letter above it. These letters are the memories where you store values, which comes up again below.

S⇔D. This is the key that confuses most students. The calculator gives exact answers first, so 1 ÷ 3 comes out as the fraction one third, and sin 45 comes out as root 2 over 2. Pressing S⇔D switches the answer to a decimal. If a question asks for an answer to one decimal place and your child is staring at a fraction, S⇔D is the fix. Pressing SHIFT then = gives the decimal straight away.

Settings to check before the exam

Calculators get borrowed and reset, so it is worth knowing how to check the settings.

• Degrees, not radians. GCSE trigonometry uses degrees. Press SHIFT then MENU to open SETUP, then 2 and 1 for degrees. A small D at the top of the screen confirms it.
• Norm, not Fix. If every answer comes out rounded to the same number of decimal places, Fix is switched on. Option 3 in SETUP sets Fix, Sci or Norm, and Norm is the normal setting.
• Fraction or decimal answers. Option 1 in SETUP switches fraction answers to decimals, if your child finds that easier for a particular paper.

A habit that saves marks, storing values

Students lose marks by rounding in the middle of a long question and then carrying the rounded number forward. The final answer drifts away from the mark scheme by a decimal place or two.

The fix is to store the full value. Press STO, then the (−) key, and the answer is saved in memory A. Later in the question, ALPHA then the (−) key, which carries the pink A, brings the exact value back. The Ans key does the same for the answer to the last sum. Students who learn this stop losing marks to rounding.

Extras that make practice quicker

A few things the online version does that a real calculator does not.

• Type on the keyboard. While the calculator is on screen, typing reaches it and the key lights up, so students learn where each key is while working at speed.
• History that stays. Every sum and answer is kept on your device. Any line can go back into a new sum with Use in sum, or be copied.
• Full screen. On a phone or tablet, a Full screen button makes the keys large enough to use.

How to practise with it

Take one calculator question from a past paper. Your child answers it on the online calculator, then does the same question on their real one without looking at the screen. If they can find every key without searching, move on to the next question. If not, repeat it.

Ten minutes a few times a week is plenty. For the skills themselves, our post on the calculator skills students lose marks on goes through ten of them, and when a question needs the working shown, our free maths calculators explain each method step by step, including the trigonometry calculator, the surds calculator and the solving equations calculator.

Open the scientific calculator and try 1 ÷ 3, then press S⇔D twice and see what happens.

Aadam, SHLC Tutors