How To Memorise Formulas Singapore Students Actually Use For O Levels

If you’re in secondary school in Singapore, you’re probably drowning in formulas:

• Algebra, indices, coordinate geometry
• Kinematics, forces, electricity
• Mole concept, gas laws, energy changes

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And on top of that, you’re expected to remember which ones are in the formula sheet (for some subjects) and which ones you must know by heart.

This guide is for you if you’ve ever thought:

• “I studied this yesterday… why is the formula gone from my brain today?”
• “During practice, I know it. During tests, my mind goes blank.”
• “There are too many formulas. How to memorise everything before O Levels?”

You’ll learn specific, proven memory techniques for maths and science formulas, tailored to Singapore’s MOE syllabus and O Level exam style. I’ll also show you how to turn those formulas into marks using a step-by-step tutorial, an exam strategy guide, worksheet-style practice (including hard variants), and a list of common mistakes to avoid.

Throughout, I’ll show you how to use Tutorly.sg, a 24/7 AI tutor website built specifically for Singapore students, to drill formulas and questions anytime. Tutorly.sg has already been mentioned on Channel NewsAsia (CNA) and used by thousands of students in Singapore, so you’re in good company.

Useful links to keep open:

• Main AI tutor page: https://tutorly.sg/ai-tutor-singapore
• Direct web app: https://tutorly.sg/app

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Step-by-step tutorial: How to actually memorise formulas (and not forget them)

Step 1: Sort your formulas into “must-memorise” and “reference”

Not every formula needs the same level of memorisation. For O Levels:

Maths examples (must-memorise):

• Algebraic identities:
  • $(a + b)^2 = a^2 + 2ab + b^2$
  • $(a - b)^2 = a^2 - 2ab + b^2$
  • $a^2 - b^2 = (a - b)(a + b)$
• Gradient formula: $m = \dfrac{y_2 - y_1}{y_1 - y_2}$ (and how to use it)
• Quadratic formula: $x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2 a}$
• Sine, cosine, tangent definitions in right-angled triangles

Physics examples (must-memorise):

• Speed: $v = \dfrac{d}{t}$
• Acceleration: $a = \dfrac{\Delta v}{\Delta t}$
• Resultant force: $F = ma$
• Work done: $W = Fd$
• Power: $P = \dfrac{W}{t}$
• Ohm’s Law: $V = IR$

Chemistry examples (must-memorise):

• Concentration: $c = \dfrac{n}{V}$ or $c = \dfrac{\text{mass}}{\text{volume}}$ (depending on context)
• Number of moles: $n = \dfrac{m}{M_r}$
• Gas laws relationships $for Combined/ Pure Chem$: $P_1V_1 = P_2V_2$ (if given in syllabus)

What to do now:

1. Take your notes / textbook.
2. Make a two-column list:
   • Column A: Must-memorise formulas (no formula sheet help)
   • Column B: Nice-to-know / reference formulas

Focus your memory energy on Column A first.

On Tutorly.sg:
Go to https://tutorly.sg/app, choose your level $e.g. Sec 3 Express$ and subject (e.g. Physics). Ask:

“List the must-memorise O Level Physics formulas I need to know without a formula sheet, grouped by topic.”

You’ll get a clean, syllabus-aligned list you can turn into your own formula bank.

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Step 2: Use “story logic” instead of blind memorisation

Formulas stick better if your brain sees meaning, not just symbols.

Example 1: $F = ma$ (Physics)

Instead of memorising “F equals m a” like a robot, understand:

• If mass is bigger, you need more force to get the same acceleration.
• If you want a bigger acceleration, you need more force for the same mass.

So mentally:

“Force is what makes mass accelerate. More mass or more acceleration = more force.”

This “story” helps you recall $F = ma$ even under stress.

Example 2: Quadratic formula

$x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2 a}$

Story logic:

• The $b^2 - 4ac$ part tells you how many roots (discriminant).
• The $\pm$ tells you two possible $x$ values.
• The negative sign $-b$ reminds you the solution is related to “undoing” the $bx$ term.

When you see a quadratic, your brain should think:

“To solve this, I need to undo the $bx$ and $c$ using that long fraction with $-b$ and the square root of $b^2 - 4ac$.”

Action: For each key formula, write a 1–2 line “story” explaining what it means, not just what it says.

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Step 3: Build short, personal mnemonics (but not for everything)

Use mnemonics only for formulas that are:

• Long, and
• Hard to remember by logic alone.

Example: Trigonometric ratios

• “SOH CAH TOA”
  • Sine = Opposite / Hypotenuse
  • Cosine = Adjacent / Hypotenuse
  • Tangent = Opposite / Adjacent

Example: Physics electricity

To remember relationships between $V$, $I$, and $R$:

• Draw a mental triangle with $V$ at the top, $I$ and $R$ at the bottom corners.
• Then:
  • $V = IR$
  • $I = \dfrac{V}{R}$
  • $R = \dfrac{V}{I}$

You can also use a phrase like “Very Important Rule” $V = I R$.

On Tutorly.sg:
Ask:

“Give me easy-to-remember mnemonics for O Level Physics formulas on forces and electricity, with Singapore examples.”

You’ll get suggestions tailored to your topics.

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Step 4: Use active recall, not re-reading

Re-reading formulas feels productive, but your brain is mostly passive. Instead, use active recall:

1. Cover-and-write

   • Fold a paper: formulas on the left, names on the right.
   • Look at the name (“Work done”), then write the formula from memory: $W = Fd$.
   • Check and correct immediately.

2. Brain dump

   • Before a study session, take 5 minutes to write all formulas you can remember from a topic.
   • Compare with your notes and fill in gaps.
   • This simulates exam conditions.

On Tutorly.sg:
You can turn it into a quick quiz. For example:

“Test me on 10 random O Level E-Maths formulas. Show the question first, then after I answer, show the correct formula and a short explanation.”

This forces you to recall, not just recognise.

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Step 5: Attach formulas to questions, not isolated flashcards

You don’t just need to memorise formulas; you need to know when to use them.

Strategy:

1. Pick one formula, e.g. $v = \dfrac{d}{t}$.
2. Do 5–10 questions that use only that formula in different contexts:
   • A car travelling 120 km in 2 hours.
   • A person walking 600 m in 10 minutes.
   • A train moving 1.2 km in 40 s.
3. As you solve, say out loud (or in your head):

   “I am using $v = \dfrac{d}{t}$ because I know distance and time, and I need speed.”

Your brain starts linking question type → formula automatically.

On Tutorly.sg:
At https://tutorly.sg/ai-tutor-singapore, you can say:

“Give me 8 basic and 4 challenging O Level Physics questions that only need $v = \dfrac{d}{t}$, and show full step-by-step solutions after I attempt.”

You’ll see the formula used repeatedly in actual exam-style questions, which is the fastest way to make it stick.

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Step 6: Use spaced repetition (not cramming the night before)

Your memory needs repeated exposure with gaps:

• Day 1: Learn formulas, do a few questions.
• Day 2: Quick 10-minute recall + 3–5 questions.
• Day 4: Repeat.
• Day 7: Repeat.
• Day 14: Repeat.

This is much more effective than one 3-hour cramming session.

You can use a simple schedule in your planner, or let Tutorly.sg help. For example:

“I want a 2-week revision plan to memorise and practise all O Level Pure Physics formulas, with daily 15-minute tasks.”

Because Tutorly is online and 24/7, you can squeeze these short sessions in between CCA, tuition, or on the bus.

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Exam strategy guide: Turning formulas into O Level marks

Memorising is just step one. You also need an exam game plan.

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1. Read the question and highlight the givens

For each question, quickly identify:

• What is given (numbers, units)
• What is asked (speed? acceleration? work done?)

Example (Physics):

A car of mass 800 kg accelerates from rest to 20 m/s in 10 s. Find the resultant force on the car.

Givens:

• $m = 800 \ \text{kg}$
• $u = 0$
• $v = 20 \ \text{m/s}$
• $t = 10 \ \text{s}$
• Find: $F$

Immediately, think:

• I know $a = \dfrac{\Delta v}{\Delta t}$
• Then $F = ma$

Write:

1. $a = \dfrac{v - u}{t} = \dfrac{20 - 0}{10} = 2.0 \ \text{m/s}^2$
2. $F = ma = 800 \times 2.0 = 1600 \ \text{N}$

2. Identify the topic → shortlist formulas

Train yourself to first ask:

“Which topic is this?”

Then:

“What are the common formulas used in this topic?”

Examples:

• Kinematics → $v = \dfrac{d}{t}$, $a = \dfrac{\Delta v}{\Delta t}$
• Forces → $F = ma$, weight $W = mg$
• Electricity → $V = IR$, $P = VI$, $E = Pt$
• Stoichiometry → $n = \dfrac{m}{M_r}$, mole ratios from balanced equations

Once you know the topic, your brain doesn’t have to search all formulas, just a small set.

On Tutorly.sg:
You can practise topic recognition by asking:

“Give me mixed-topic O Level Physics questions and after each one, tell me which topic it’s from and which formula I should have used.”

This helps you build the “question → topic → formula” chain.

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3. Write the formula first, then substitute

In exams, don’t jump straight to numbers. Use this structure:

1. Write the formula: $P = \dfrac{W}{t}$
2. Substitute: $P = \dfrac{2000}{10}$
3. Calculate: $P = 200 \ \text{W}$

Why this helps:

• You get method marks even if your final answer is wrong.
• It reduces careless mistakes because you see clearly which value goes where.
• It reinforces memorisation every time you write the formula.

Same for Maths:

1. $A = \dfrac{1}{2}bh$
2. $A = \dfrac{1}{2} \times 8 \times 5$
3. $A = 20 \ \text{cm}^2$

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4. Always check units and reasonableness

After getting an answer, ask:

• Are the units correct? $e.g. speed in m/s, not m/s²$
• Is the magnitude reasonable? $e.g. a car speed of 5000 m/s is obviously wrong$

This can catch formula mix-ups, like accidentally using $P = \dfrac{W}{t}$ when the question actually asked for energy $W$.

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5. Use formula sheet wisely (for subjects that have one)

For O Level E-Maths and some sciences, you may have a formula sheet. But:

• Don’t rely on it for basic formulas (wastes time).
• Use it to double-check complicated ones (e.g. volume of sphere, surface area of cone).

Train yourself during practice:

• Only look at the formula sheet after you’ve tried to recall it.
• This keeps your recall muscles strong.

On Tutorly.sg:
You can practise “closed book” by saying:

“Give me 10 O Level E-Maths questions that require formulas from the formula sheet, but don’t show the formulas until after I answer.”

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Worksheet practice: From basic to hard exam variants

Let’s go through some practice-style questions to see formulas in action. Try them yourself first, then compare with the worked solution.

A. Maths: Algebra & coordinate geometry

Q 1 (Basic): Expanding algebraic identities

Expand and simplify: $(3 x + 2)^2$

Solution:

Use $(a + b)^2 = a^2 + 2ab + b^2$ with $a = 3 x$, $b = 2$:

• $(3 x)^2 = 9 x^2$
• $2ab = 2(3 x)(2) = 12 x$
• $b^2 = 4$

So $(3 x + 2)^2 = 9 x^2 + 12 x + 4$.

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Q 2 (Intermediate): Coordinate geometry gradient

Find the gradient of the line joining points $A(2, 5)$ and $B(8, 17)$.

Solution:

Use gradient formula:
$m = \dfrac{y_2 - y_1}{x_2 - x_1}$

Let $A(2,5)$ be $(x_1, y_1)$ and $B(8,17)$ be $(x_2, y_2)$:

$m = \dfrac{17 - 5}{8 - 2} = \dfrac{12}{6} = 2$

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Q 3 (Hard): Equation of a line – O Level style

A line passes through points $P(1, -2)$ and $Q(5, 6)$.

1. Find the gradient of the line.
2. Find the equation of the line in the form $y = mx + c$.

Solution:

1. Gradient:
   $m = \dfrac{6 - (-2)}{5 - 1} = \dfrac{8}{4} = 2$

2. Use $y = mx + c$ with $m = 2$ and point $P(1, -2)$:

   Substitute:
   $-2 = 2(1) + c \Rightarrow -2 = 2 + c \Rightarrow c = -4$

   So the equation is $y = 2 x - 4$.

Key formulas used:

• $m = \dfrac{y_2 - y_1}{x_2 - x_1}$
• $y = mx + c$

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B. Physics: Kinematics and forces

Q 4 (Basic): Speed

A student jogs 2.4 km in 20 minutes. Find her average speed in m/s.

Solution:

1. Convert units:

   • $2.4 \ \text{km} = 2400 \ \text{m}$
   • $20 \ \text{min} = 20 \times 60 = 1200 \ \text{s}$

2. Use $v = \dfrac{d}{t}$:

   $v = \dfrac{2400}{1200} = 2.0 \ \text{m/s}$

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Q 5 (Intermediate): Acceleration

A bicycle increases its speed from 5 m/s to 11 m/s in 3 s. Find the acceleration.

Solution:

Use $a = \dfrac{\Delta v}{\Delta t}$:

$a = \dfrac{11 - 5}{3} = \dfrac{6}{3} = 2.0 \ \text{m/s}^2$

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Q 6 (Hard): Multi-step $F = ma$ question – typical O Level style

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A 600 kg car is travelling at 15 m/s. It accelerates uniformly to 25 m/s in 5 s.

1. Find the acceleration.
2. Find the resultant force acting on the car.
3. Calculate the distance travelled during this time (you may use $s = \dfrac{(u + v)}{2} t$).

Solution:

1. Acceleration:

   $a = \dfrac{v - u}{t} = \dfrac{25 - 15}{5} = \dfrac{10}{5} = 2.0 \ \text{m/s}^2$

2. Resultant force:

   $F = ma = 600 \times 2.0 = 1200 \ \text{N}$

3. Distance travelled (using average speed formula):

   $s = \dfrac{u + v}{2} \times t = \dfrac{15 + 25}{2} \times 5 = \dfrac{40}{2} \times 5 = 20 \times 5 = 100 \ \text{m}$

Key formulas used:

• $a = \dfrac{\Delta v}{\Delta t}$
• $F = ma$
• $s = \dfrac{u + v}{2} t$

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C. Chemistry: Moles and concentration

Q 7 (Basic): Number of moles

Calculate the number of moles in 10 g of magnesium. $Relative atomic mass of Mg = 24$

Solution:

Use $n = \dfrac{m}{M_r}$:

$n = \dfrac{10}{24} \approx 0.417 \ \text{mol}$

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Q 8 (Intermediate): Mass from moles

How many grams of carbon dioxide are there in 0.5 mol of $\text{CO}_2$? (Relative molecular mass of $\text{CO}_2 = 44$)

Solution:

Use $m = n \times M_r$:

$m = 0.5 \times 44 = 22 \ \text{g}$

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Q 9 (Hard): Stoichiometry – O Level style

Magnesium reacts with hydrochloric acid according to the equation:

$\text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2$

6.0 g of magnesium is reacted with excess hydrochloric acid.

1. Calculate the number of moles of magnesium used. $Ar of Mg = 24$
2. Hence, calculate the number of moles of hydrogen gas produced.
3. Find the mass of hydrogen gas produced. $Ar of H = 1$

Solution:

1. Moles of Mg:

   $n(\text{Mg}) = \dfrac{m}{M_r} = \dfrac{6.0}{24} = 0.25 \ \text{mol}$

2. From the equation, 1 mol Mg → 1 mol $\text{H}_2$
   So moles of $\text{H}_2$ produced = 0.25 mol.

3. Mass of $\text{H}_2$:

   $M_r(\text{H}_2) = 2 \times 1 = 2$

   $m(\text{H}_2) = n \times M_r = 0.25 \times 2 = 0.50 \ \text{g}$

Key formulas used:

• $n = \dfrac{m}{M_r}$
• $m = n \times M_r$
• Mole ratios from balanced chemical equation

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Using Tutorly.sg to generate endless practice (including harder variants)

The questions above are just a sample. For real improvement, you need many questions, especially:

• Slightly tweaked versions (to test if you really understand)
• Harder variants that combine multiple formulas in one question

On https://tutorly.sg/app, you can do things like:

• “Give me 15 O Level Pure Physics questions that combine $F = ma$ and $W = Fd$, with increasing difficulty, and show step-by-step solutions after I attempt each one.”
• “Generate a worksheet of 20 E-Maths algebra identity questions, including 5 very challenging ones similar to O Level Section B, and explain each solution.”

Because Tutorly shows the final answer first, then walks you through the step-by-step working, you can compare your own method and see where you went wrong, without needing a human tutor beside you.

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Common mistakes Singapore students make with formulas

Let’s fix the errors that cost the most marks in O Levels.

1. Mixing up similar-looking formulas

Examples:

• Using $P = \dfrac{W}{t}$ when the question asks for energy $W$ (should rearrange to $W = Pt$).
• Confusing speed and acceleration formulas:
  • Speed: $v = \dfrac{d}{t}$
  • Acceleration: $a = \dfrac{\Delta v}{\Delta t}$

How to avoid:

• Always write the general formula first, then rearrange.
• Train with rearranging practice:
  • From $P = \dfrac{W}{t}$, derive $W = Pt$ and $t = \dfrac{W}{P}$.
  • From $V = IR$, derive $I = \dfrac{V}{R}$ and $R = \dfrac{V}{I}$.

On Tutorly.sg:
Ask:

“Give me 15 short questions where I need to rearrange Physics formulas like $V = IR$ and $P = \dfrac{W}{t}$ to make different variables the subject.”

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Ready to practise?

If you want a Singapore-focused AI tutor you can use immediately $website, no sign-up$, try Tutorly here:

• https://tutorly.sg/ai-tutor-singapore
• https://tutorly.sg/app

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