🔢 Calculator Hacks

Essential Calculator Skills

Mastering Your Scientific Calculator

Your calculator is a powerful tool — but only if you know how to use it properly. Here are the essential skills that can save you marks.

Key Buttons You Must Know

Fraction Button $\boxed{a\frac{b}{c}}$ or $\boxed{\frac{\square}{\square}}$

Use for all fraction calculations to avoid decimal conversion errors:

Enter $\frac{3}{4}$ as: 3 a b/c 4
Convert between mixed numbers and improper fractions using SHIFT + a b/c

Power Button $\boxed{x^y}$ or $\boxed{\wedge}$

$5^3$ = 5 ^ 3 = gives 125
For square roots: $\sqrt{16}$ = √ 16 =
For cube roots: $\sqrt[3]{27}$ = SHIFT ^ 3 27 =

Brackets $\boxed{(}$ $\boxed{)}$

Essential for BIDMAS!

❌ 5 + 3 × 4 might give 32 (if calculated left-to-right by mistake) ✅ (5 + 3) × 4 definitely gives 32

Always use brackets when:

Dividing by an expression: $\frac{20}{4+1}$ = 20 ÷ (4 + 1)
Using negative bases: $(-3)^2$ = ( (-) 3 ) ^ 2 = 9
Complex fractions

Memory Functions

STO — Store a value (useful for long calculations)
RCL or Ans — Recall the stored value
Ans — Uses your previous answer (great for iterative calculations)

Angle Mode: Check Before Every Exam!

Calculator Mode Check

Your calculator has three angle modes:

D = Degrees (what you need for GCSE)
R = Radians (A-Level only)
G = Gradians (never used in UK exams)

Check it's on D (Degrees):

Press MODE or SETUP
Look for D at the top of your display

Quick test: Calculate $\sin(90)$. If the answer is 1, you're in degrees ✓

Standard Form on Calculator

Entering standard form: $4.5 \times 10^6$ = 4.5 ×10^x or EXP 6

Reading the display:

$4.5_{06}$ or $4.5\text{E}06$ means $4.5 \times 10^6$
$3.2_{-04}$ means $3.2 \times 10^{-4}$

Trigonometry Functions

Finding an angle (inverse trig):

$\sin^{-1}(0.5)$ = SHIFT sin 0.5 = gives 30°
$\cos^{-1}(0.5)$ = SHIFT cos 0.5 = gives 60°
$\tan^{-1}(1)$ = SHIFT tan 1 = gives 45°

Common Calculator Mistakes

Mistake 1: Wrong bracket placement

$\frac{8}{2(2+2)}$ — the internet famously argued about this!
Always use brackets to make your intention clear

Mistake 2: Negative number powers

$-3^2 = -9$ (squares the 3, then makes it negative)
$(-3)^2 = 9$ (squares negative 3)

Mistake 3: Forgetting to close brackets

Calculator may give unexpected results if brackets don't match

Mistake 4: Rounding too early

Keep full calculator precision during working
Only round your final answer

Prime Factorisation Function

Many scientific calculators can find prime factors:

Enter the number
Press FACT (or SHIFT + specific button)
Calculator displays: $180 = 2^2 \times 3^2 \times 5$

Table Function (for Graphs)

Your calculator can generate coordinate tables:

Go to TABLE mode
Enter your equation (e.g., $y = 2x + 1$)
Set start, end, and step values
Calculator produces the coordinates

This is brilliant for checking your graph plots!