Using A Calculator

Why Calculator Skills Matter

• Scientific calculators have many special functions you need to master.
• You'll use them in IGCSE Maths and other subjects like Science.
• Different models work differently; learn your specific calculator's features.

What should you check before starting a calculator-based exam?

• The battery level
• The angle unit is set to degrees
• The calculator is in STAT mode
• The display brightness

Essential Settings

• Use MODE to set to 'MATH' mode for natural display.
• Angle unit must be degrees (look for 'D' symbol).
• Use S⇔D to switch between exact (fraction) and approximate (decimal) answers.

Which of these are true about calculator settings?

• The 'D' symbol means degrees mode is active.
• You should reset your calculator before an exam to clear settings.
• MATH mode shows answers only as fractions.

Using Brackets Correctly

• Use brackets around negative numbers: $(-3)^{2}$ gives 9, $but -3^{2}$ gives -9.
• Use the (-) button for negative values, not the minus sign.
• Always close brackets after functions like sin(45°).

What is the result $of -3^{2}$ on a calculator?

• 9
• -9
• 6
• -6

Trigonometry Buttons

• Use sin, cos, tan for sides; use sin⁻¹, cos⁻¹, tan⁻¹ (via SHIFT) for angles.
• Always close the bracket after typing the angle: sin(30).
• Check degrees mode before trig calculations.

To find an angle, use the ____ function accessed via the ____ button.

Standard Form and π

• Use ×10ˣ button for standard form; modern displays show it as 2×10⁵.
• π is often near the standard form button, sometimes via SHIFT.
• Older models may use 'E' notation, e.g., 2E5.

How would you enter 3×10⁴ on a modern scientific calculator?

• $3 \times 10 ^ 4$
• $3 \times$ 10ˣ 4
• 3E4
• All of the above

The Ans and Table Functions

• Ans recalls the last answer; use it to avoid rounding intermediate steps.
• Table mode helps complete tables of values quickly and reduces errors.

Which statements about Ans and Table are true?

• Ans stores the last calculated result.
• Table mode can be used for drawing graphs.
• Ans can only be used once per calculation.

Time Calculations

• Use the ° ' '' button to enter time in hours/minutes/seconds.
• Example: 3 minutes 45 seconds $= 0^{\circ}3'45''$.
• The same button converts between decimal and sexagesimal time.

How do you enter 2 hours 30 minutes on a calculator?

• 2°30'
• 2.5
• 2°30''
• 2:30

Worked Example: Full Calculator Display

• Type the entire calculation in one go using the fraction button.
• Write down intermediate steps with '...' to show no rounding.
• Example: $\sqrt{4.69} / (0.343 + sin45^{\circ}) = 2.901406085$.

When showing working, write down all digits and use ____ to indicate the number continues.

Worked Example: Substituting Values

• For $a = (p+q)/(p^{2}q)$, substitute p=1.2×10⁻³ and q=7.83×10⁵.
• Calculate numerator and denominator separately, writing down full display.
• Round only the final answer to the required significant figures.

What is the value of $a = (p+q)/(p^{2}q)$ with p=1.2×10⁻³, q=7.83×10⁵ to 3 s.f.?

• 694000
• 694444
• 694
• 694000.4455

Worked Example: Table of Values

• Use brackets around negative x values: $(-3)^{3} - 6(-3) + 1$.
• Use the (-) button for negative numbers.
• Use arrow keys to edit previous inputs for efficiency.

For $y = x^{3} - 6x + 1$, when x = -2, y = ____.