G3 Mathematics (K310), was O-Level E-Math (4052)

O-Level E-Math formula sheet

The E-Math paper prints a short list of formulas on its second page. Below is every formula on that list, with a worked example for each, and then the longer list the paper does not give you: the quadratic formula, every area and volume outside the list, gradients, indices, probability and the circle properties.

Given in the exam

SEAB prints these at the front of every paper. Know what each letter means and when to use each one, so you are not reading the list for the first time on the day.

Compound interest

  • Total amount

    A=P(1+r100)nA = P\left(1 + \dfrac{r}{100}\right)^{n}

    r is the rate for one period and n the number of periods.

    Example: $5000 at 3% a year for 2 years: 5000 × 1.03² = $5304.50.

Mensuration

  • Curved surface area of a cone

    πrl\pi r l

    Example: r = 3 cm, slant height l = 5 cm: 15π ≈ 47.1 cm².

  • Surface area of a sphere

    4πr24\pi r^{2}

    Example: r = 2 cm: 16π ≈ 50.3 cm².

  • Volume of a cone

    13πr2h\dfrac{1}{3}\pi r^{2} h

    Example: r = 3 cm, h = 4 cm: 12π ≈ 37.7 cm³.

  • Volume of a sphere

    43πr3\dfrac{4}{3}\pi r^{3}

    Example: r = 3 cm: 36π ≈ 113 cm³.

  • Area of a triangle

    12absin⁡C\dfrac{1}{2}ab\sin C

    C is the angle between sides a and b.

    Example: a = 8 cm, b = 5 cm, C = 30°: ½ × 8 × 5 × 0.5 = 10 cm².

  • Arc length

    rθr\theta

    θ in radians.

    Example: r = 6 cm, θ = 1.2 rad: 7.2 cm.

  • Sector area

    12r2θ\dfrac{1}{2}r^{2}\theta

    θ in radians.

    Example: r = 6 cm, θ = 1.2 rad: ½ × 36 × 1.2 = 21.6 cm².

Trigonometry

  • Sine rule

    asin⁡A=bsin⁡B=csin⁡C\dfrac{a}{\sin A} = \dfrac{b}{\sin B} = \dfrac{c}{\sin C}

    Use it when you know a side and the angle opposite it.

    Example: a = 10 cm, A = 40°, B = 65°: b = 10 sin 65° ÷ sin 40° ≈ 14.1 cm.

  • Cosine rule

    a2=b2+c2−2bccos⁡Aa^{2} = b^{2} + c^{2} - 2bc\cos A

    Use it for two sides and the angle between them, or for three sides.

    Example: b = 5 cm, c = 7 cm, A = 60°: a² = 25 + 49 − 35 = 39, so a ≈ 6.24 cm.

Statistics

  • Mean

    xˉ=∑fx∑f\bar{x} = \dfrac{\sum fx}{\sum f}

    For grouped data, x is the mid-value of each class.

    Example: Scores 1, 2, 3 with frequencies 2, 5, 3: Σfx = 21, Σf = 10, mean = 2.1.

  • Standard deviation

    ∑fx2∑f−(∑fx∑f)2\sqrt{\dfrac{\sum fx^{2}}{\sum f} - \left(\dfrac{\sum fx}{\sum f}\right)^{2}}

    Example: Same data: Σfx² = 49, so √(4.9 − 2.1²) = √0.49 = 0.7.

Not given: learn these by heart

The paper does not print any of these, and the questions expect you to know them.

Numbers, percentage and rate

  • Simple interest

    I=PRT100I = \dfrac{PRT}{100}

    Example: $2000 at 4% a year for 3 years: I = $240.

  • Percentage change

    changeoriginal×100%\dfrac{\text{change}}{\text{original}} \times 100\%

    Example: 80 rises to 92: 12 ÷ 80 × 100% = 15% increase.

  • Reverse percentage

    original=new1±rate\text{original} = \dfrac{\text{new}}{1 \pm \text{rate}}

    Example: $64 after 20% off: 64 ÷ 0.8 = $80 before.

  • Standard form

    A×10n,1≤A<10A \times 10^{n}, \quad 1 \le A < 10

    Example: 0.000 52 = 5.2 × 10⁻⁴.

  • Laws of indices

    am×an=am+n,am÷an=am−na^{m} \times a^{n} = a^{m+n}, \quad a^{m} \div a^{n} = a^{m-n}
    (am)n=amn,a0=1,a−n=1an(a^{m})^{n} = a^{mn}, \quad a^{0} = 1, \quad a^{-n} = \dfrac{1}{a^{n}}
    a1n=an,amn=(an)ma^{\frac{1}{n}} = \sqrt[n]{a}, \quad a^{\frac{m}{n}} = \left(\sqrt[n]{a}\right)^{m}

    Example: 8^(2/3) = (∛8)² = 2² = 4.

  • Speed

    speed=distancetime\text{speed} = \dfrac{\text{distance}}{\text{time}}
    average speed=total distancetotal time\text{average speed} = \dfrac{\text{total distance}}{\text{total time}}

    Example: 72 km/h ÷ 3.6 = 20 m/s.

  • Direct and inverse proportion

    y=kxandy=kxy = kx \quad\text{and}\quad y = \dfrac{k}{x}

    Example: y = k/x and y = 6 when x = 2, so k = 12; when x = 3, y = 4.

  • Map scale

    area scale=(length scale)2\text{area scale} = (\text{length scale})^{2}

    Example: 1 : 50 000 means 1 cm to 0.5 km, so 1 cm² to 0.25 km².

Algebra

  • Special products

    (a+b)2=a2+2ab+b2(a + b)^{2} = a^{2} + 2ab + b^{2}
    (a−b)2=a2−2ab+b2(a - b)^{2} = a^{2} - 2ab + b^{2}
    a2−b2=(a+b)(a−b)a^{2} - b^{2} = (a + b)(a - b)

    Example: 51² − 49² = (51 + 49)(51 − 49) = 200.

  • Quadratic formula

    x=−b±b2−4ac2ax = \dfrac{-b \pm \sqrt{b^{2} - 4ac}}{2a}

    Not on the E-Math list. The A-Math list has it; this paper does not.

    Example: x² − 3x − 1 = 0: x = (3 ± √13) ÷ 2, so x ≈ 3.30 or −0.303.

  • Completing the square

    x2+px+q=(x+p2)2−(p2)2+qx^{2} + px + q = \left(x + \dfrac{p}{2}\right)^{2} - \left(\dfrac{p}{2}\right)^{2} + q

    Example: x² + 6x + 1 = (x + 3)² − 8, so the minimum point is (−3, −8).

  • nth term of a linear sequence

    Tn=a+(n−1)dT_{n} = a + (n - 1)d

    Example: 5, 8, 11, ...: a = 5, d = 3, so Tₙ = 3n + 2.

Coordinates and graphs

  • Gradient

    m=y2−y1x2−x1m = \dfrac{y_{2} - y_{1}}{x_{2} - x_{1}}

    Example: (1, 2) and (4, 11): m = 9 ÷ 3 = 3.

  • Length of a line segment

    (x2−x1)2+(y2−y1)2\sqrt{(x_{2} - x_{1})^{2} + (y_{2} - y_{1})^{2}}

    Example: (1, 2) and (4, 6): √(9 + 16) = 5.

  • Straight line

    y=mx+cy = mx + c

    c is where the line crosses the y-axis.

    Example: Gradient 3 through (0, −2): y = 3x − 2.

Angles, triangles and circles

  • Pythagoras' theorem

    a2+b2=c2a^{2} + b^{2} = c^{2}

    c is the side opposite the right angle.

    Example: Sides 6 cm and 8 cm: hypotenuse = √100 = 10 cm.

  • Trigonometric ratios

    sin⁡θ=opphyp,cos⁡θ=adjhyp,tan⁡θ=oppadj\sin\theta = \dfrac{\text{opp}}{\text{hyp}}, \quad \cos\theta = \dfrac{\text{adj}}{\text{hyp}}, \quad \tan\theta = \dfrac{\text{opp}}{\text{adj}}

    Right-angled triangles only.

    Example: Hypotenuse 10 cm, angle 30°: opposite = 10 sin 30° = 5 cm.

  • Angles of a polygon

    interior sum=(n−2)×180∘\text{interior sum} = (n - 2) \times 180^{\circ}
    exterior sum=360∘\text{exterior sum} = 360^{\circ}

    Example: A regular hexagon: each exterior angle 360° ÷ 6 = 60°, each interior angle 120°.

  • Circle properties

    ∠AOB=2∠ACB\angle AOB = 2\angle ACB
    angle in a semicircle=90∘\text{angle in a semicircle} = 90^{\circ}
    tangent⊥radius\text{tangent} \perp \text{radius}
    cyclic quadrilateral: ∠A+∠C=180∘\text{cyclic quadrilateral: } \angle A + \angle C = 180^{\circ}

    O is the centre and C is on the circle. Also: angles in the same segment are equal, and tangents from one point are equal.

    Example: An angle of 35° at the circumference stands on the same arc as 70° at the centre.

  • Similar figures

    A1A2=(l1l2)2,V1V2=(l1l2)3\dfrac{A_{1}}{A_{2}} = \left(\dfrac{l_{1}}{l_{2}}\right)^{2}, \quad \dfrac{V_{1}}{V_{2}} = \left(\dfrac{l_{1}}{l_{2}}\right)^{3}

    Example: Lengths 2 : 3 give areas 4 : 9 and volumes 8 : 27.

Mensuration

  • Plane figures

    parallelogram=bh,trapezium=12(a+b)h\text{parallelogram} = bh, \quad \text{trapezium} = \dfrac{1}{2}(a + b)h
    circle: A=πr2,C=2πr\text{circle: } A = \pi r^{2}, \quad C = 2\pi r

    Example: A trapezium with parallel sides 5 cm and 9 cm, height 4 cm: 28 cm².

  • Prisms and cylinders

    V=cross-section area×lengthV = \text{cross-section area} \times \text{length}
    cylinder: V=πr2h,curved surface=2πrh\text{cylinder: } V = \pi r^{2}h, \quad \text{curved surface} = 2\pi rh

    Example: A cylinder with r = 2 cm, h = 5 cm: V = 20π ≈ 62.8 cm³.

  • Volume of a pyramid

    13×base area×h\dfrac{1}{3} \times \text{base area} \times h

    Example: A 6 cm square base, height 5 cm: ⅓ × 36 × 5 = 60 cm³.

  • Radians

    π rad=180∘\pi \text{ rad} = 180^{\circ}

    Example: 1.2 rad = 1.2 × 180° ÷ π ≈ 68.8°.

  • Area of a segment

    12r2θ−12r2sin⁡θ\dfrac{1}{2}r^{2}\theta - \dfrac{1}{2}r^{2}\sin\theta

    Sector minus triangle. θ in radians, and the calculator in radian mode.

    Example: r = 6 cm, θ = 1.2 rad: 21.6 − 18 sin 1.2 ≈ 4.82 cm².

  • Unit conversions

    1 m2=10 000 cm2,1 m3=1 000 000 cm31\text{ m}^{2} = 10\,000\text{ cm}^{2}, \quad 1\text{ m}^{3} = 1\,000\,000\text{ cm}^{3}

    Example: 3.5 m² = 35 000 cm².

Vectors

  • Magnitude

    ∣(xy)∣=x2+y2\left|\begin{pmatrix} x \\ y \end{pmatrix}\right| = \sqrt{x^{2} + y^{2}}

    Example: The vector (3, −4) has magnitude 5.

  • Vector between two points

    AB→=OB→−OA→\overrightarrow{AB} = \overrightarrow{OB} - \overrightarrow{OA}

    Example: A(1, 2) and B(4, 6): AB = (3, 4).

Statistics and probability

  • Median and quartiles

    median: the n+12th value,IQR=Q3−Q1\text{median: the } \tfrac{n+1}{2}\text{th value}, \quad \text{IQR} = Q_{3} - Q_{1}

    Example: 9 values in order: the median is the 5th.

  • Probability

    P(A)=favourable outcomesall outcomes,P(not A)=1−P(A)P(A) = \dfrac{\text{favourable outcomes}}{\text{all outcomes}}, \quad P(\text{not } A) = 1 - P(A)
    exclusive: P(A or B)=P(A)+P(B)\text{exclusive: } P(A \text{ or } B) = P(A) + P(B)
    independent: P(A and B)=P(A)×P(B)\text{independent: } P(A \text{ and } B) = P(A) \times P(B)

    Example: Two fair coins: P(two heads) = ½ × ½ = ¼.

Use the formulas on a paper

A free E-Math paper in the O-Level's two-paper shape for each year, with every answer, to print or sit online.

Questions parents ask

Is this the official E-Math formula list?
The first half has every formula on SEAB's list for G3 Mathematics (K310), set out in our own layout with our own examples. The paper prints the list at the front, so the second half, what it leaves out, is the part to learn. Scholar Tests is not connected with MOE, SEAB or Cambridge.
Did the formula list change with the SEC?
No. From 2027 the O-Level becomes the Secondary Education Certificate, and the subject is called G3. SEAB's 2027 syllabus has the same topics and the same formula list as the 2026 O-Level one, so this sheet serves both.
How should answers be given?
To 3 significant figures unless the question says otherwise, and angles in degrees to 1 decimal place. Use your calculator's π or 3.142, unless the answer is wanted in terms of π. Show the working: essential working left out loses marks.
Can I print it?
Yes. The print button gives both halves on plain paper, without this page's buttons or questions. Keep it beside you while you do past-year and practice papers until you no longer need to look.