SSC CPO maths formulas: one-page revision sheet for Paper I Quant

Mathematical formulas written on a blackboard
Photo: Wallpoper (public domain), via Wikimedia Commons

In the Quantitative Aptitude part of SSC CPO Paper I you have 15 minutes for 25 questions, so there is no time to derive a formula in the exam. This sheet collects the formulas behind most Paper I Quant questions, grouped as the syllabus groups them. Revise it once a day in the last two weeks before Paper I (23 to 28 November 2026, proposed).

Percentage, profit and discount

Idea Formula
x% of y x × y ÷ 100
Percentage change (new − old) ÷ old × 100
Successive changes of a% and b% a + b + ab ÷ 100
Profit % profit ÷ cost price × 100
Selling price cost × (100 + profit%) ÷ 100
Discount % discount ÷ marked price × 100
Price rises r%: cut consumption by r ÷ (100 + r) × 100 %

Example: two successive discounts of 20% and 10% equal 20 + 10 − 200 ÷ 100 = 28%.

Interest

Idea Formula
Simple interest P × R × T ÷ 100
Compound amount P × (1 + R/100)ᵀ
CI − SI for 2 years P × (R/100)²
Money doubles in T years at CI it becomes 4 times in 2T, 8 times in 3T

Ratio, average and mixture

Idea Formula
Average sum ÷ number
A : B = a : b and B : C = c : d A : B : C = ac : bc : bd
Alligation cheaper : dearer = (dearer − mean) : (mean − cheaper)
Average of 1 to n (n + 1) ÷ 2

Time, work and distance

Idea Formula
Together (A in a days, B in b days) ab ÷ (a + b) days
Speed distance ÷ time; km/h × 5/18 = m/s
Average speed, equal distances 2xy ÷ (x + y)
Train passing a pole train length ÷ speed
Train passing a platform (train + platform) ÷ speed
Boats still water = (down + up) ÷ 2; stream = (down − up) ÷ 2

Number system

Idea Rule
HCF × LCM product of two numbers
Divisible by 3, 9 digit sum divisible by 3, 9
Divisible by 11 alternate digit sums differ by 0 or a multiple of 11
Number of factors of pᵃ qᵇ (a + 1)(b + 1)
Unit digits of powers repeat every 4 (2, 3, 7, 8)

Algebra identities

  • (a + b)² = a² + 2ab + b² and (a − b)² = a² − 2ab + b²
  • a² − b² = (a + b)(a − b)
  • a³ + b³ = (a + b)³ − 3ab(a + b); a³ − b³ = (a − b)³ + 3ab(a − b)
  • If x + 1/x = k: x² + 1/x² = k² − 2 and x³ + 1/x³ = k³ − 3k
  • (a + b + c)² = a² + b² + c² + 2(ab + bc + ca)
  • If a + b + c = 0, then a³ + b³ + c³ = 3abc

Geometry

  • Angles of a triangle add to 180°; exterior angle = sum of the two opposite interior angles.
  • Sum of interior angles of an n-sided polygon = (n − 2) × 180°; each exterior angle of a regular polygon = 360° ÷ n.
  • Pythagorean triples: 3-4-5, 5-12-13, 8-15-17, 7-24-25.
  • A perpendicular from the centre bisects a chord: r² = (half chord)² + distance².
  • Tangent length from a point at distance d from the centre: √(d² − r²).
  • Similar triangles: ratio of areas = (ratio of sides)².

Mensuration

Shape Area or volume
Triangle ½ × base × height; Heron: √(s(s − a)(s − b)(s − c))
Equilateral triangle (√3/4) × a²
Circle πr²; circumference 2πr
Cuboid lbh; diagonal √(l² + b² + h²)
Cube a³; surface 6a²
Cylinder πr²h; curved surface 2πrh
Cone (1/3)πr²h; curved surface πrl
Sphere (4/3)πr³; surface 4πr²
Hemisphere (2/3)πr³

Trigonometry

Angle 0° 30° 45° 60° 90°
sin 0 1/2 1/√2 √3/2 1
cos 1 √3/2 1/√2 1/2 0
tan 0 1/√3 1 √3 not defined
  • sin²θ + cos²θ = 1; sec²θ − tan²θ = 1; cosec²θ − cot²θ = 1
  • If sec θ + tan θ = k, then sec θ − tan θ = 1/k.

How to use this sheet

Read it once a day, then cover the right-hand column and say each formula aloud. Use it in practice: every Quant part of our SSC CPO mock tests has explanations that name the formula used. For which topics carry the most marks, see SSC CPO Quantitative Aptitude: important topics.

Frequently asked questions

Which maths formulas are most important for SSC CPO?

Percentage, profit and discount, interest, time and work, speed and distance, the algebra identities and the standard trigonometric values. These cover most of the 25 Quant questions in Paper I.

Is a calculator allowed in SSC CPO?

No. Electronic devices are not allowed in the exam hall, so practise mental shortcuts like "cost = 100" and the units method for work.

How do I remember SSC CPO formulas?

Revise from one page daily, use each formula in practice questions the same day, and write the ones you forget in your mistake notebook.