Calculator Skills
Working with Fractions on Your Calculator
A scientific calculator keeps answers as exact fractions and surds, which matters when SPM wants an exact answer rather than a rounded decimal.
Keep exact answers exact
When a question asks for an exact value, leave it as a fraction or surd rather than converting to a decimal. Most scientific calculators toggle between exact and decimal forms with a single key, so you can check both without losing accuracy.
A worked keystroke sequence for adding fractions
- To work out 2/3 + 1/4, press the fraction key (the stacked a-over-b key).
- Type 2 for the numerator, move down with the cursor, and type 3 for the denominator.
- Press +, then the fraction key again, and enter 1 over 4 the same way.
- Press = . The calculator shows 11/12, already in lowest terms.
- The keypad kept the exact fraction throughout, so you never rounded 0.9166… by hand.
Check the fraction against its decimal
After you get an exact fraction, press the fraction-decimal toggle to see its decimal value, then estimate whether that decimal is sensible. Here 11/12 shows as about 0.9167, which sits just under 1, exactly what you would expect from adding two proper fractions close to a whole.
If the decimal looks wrong, you probably mistyped a numerator or denominator.
Source:SPM: Format Pentaksiran mulai 2021, Matematik (1449)
Frequently asked questions
The question wants an exact answer, should I use decimals or fractions?
Give the exact fraction. Numbers like 1/3 or 2/7 never end as decimals, so writing 0.33 or 0.29 introduces rounding error and can cost accuracy marks.
Keep the calculator in fraction display, and only convert to a decimal if the question specifically asks for one.
My mixed number keeps turning into a strange answer, why?
You are probably entering it as a whole number times a fraction. Use the dedicated mixed-number key so 2¾ is read as two and three-quarters, not 2 × 3/4.
Without that key the calculator treats the parts as a multiplication and the value comes out wrong.
Can the calculator keep surds like √2 exact too?
Many scientific calculators do keep surds exact when the mode allows it, so √8 may display as 2√2 rather than 2.828. This is useful when a question asks for the answer in surd form.
If it shows a decimal instead, check that the calculator is set to exact rather than decimal output.