SSC CHSL Formula Sheet
Ten formulas, what each one is for, and a worked example.
SSC CHSL maths is mostly arithmetic, with some basic geometry, mensuration and trigonometry. Percentages, profit and loss, discount and interest make up the core.
These ten formulas cover that core, with a worked discount example.
You save ₹350
- Full-length Tier 1 & Tier 2 mocks
- Timed sectional drills
- General Awareness bank
One payment, no subscription
The 10 Formulas
1
Formula
Percentage change
Expression
(New − Old) ÷ Old × 100
Use it for
Growth and fall in values, and the base of most DI questions.
2
Formula
Profit %
Expression
(SP − CP) ÷ CP × 100
Use it for
Profit or loss on cost price.
3
Formula
Discount and marked price
Expression
SP = MP × (1 − Discount/100)
Use it for
Selling price after a discount on the marked price.
4
Formula
Successive percentage change
Expression
Net % = a + b + (a × b) ÷ 100
Use it for
Two changes in a row, such as a rise then a discount.
5
Formula
Simple interest
Expression
SI = P × R × T ÷ 100
Use it for
Interest that isn't added back to the principal.
6
Formula
Compound interest
Expression
A = P × (1 + R/100)ᵀ; CI = A − P
Use it for
Interest compounded once a year.
7
Formula
Time and work (two people)
Expression
Days together = (a × b) ÷ (a + b)
Use it for
When A alone takes a days and B alone takes b days.
8
Formula
Average
Expression
Sum of observations ÷ Number of observations
Use it for
Averages, and finding a missing or replaced value.
9
Formula
Standard trig values
Expression
sin 30° = 1/2, sin 45° = 1/√2, sin 60° = √3/2; tan 45° = 1
Use it for
Heights and distances and value questions.
10
Formula
Rectangle and square
Expression
Rectangle: area = l × b, perimeter = 2(l + b); Square: area = a²
Use it for
Area and perimeter questions.
| # | Formula | Expression | Use it for |
|---|---|---|---|
| 1 | Percentage change | (New − Old) ÷ Old × 100 | Growth and fall in values, and the base of most DI questions. |
| 2 | Profit % | (SP − CP) ÷ CP × 100 | Profit or loss on cost price. |
| 3 | Discount and marked price | SP = MP × (1 − Discount/100) | Selling price after a discount on the marked price. |
| 4 | Successive percentage change | Net % = a + b + (a × b) ÷ 100 | Two changes in a row, such as a rise then a discount. |
| 5 | Simple interest | SI = P × R × T ÷ 100 | Interest that isn't added back to the principal. |
| 6 | Compound interest | A = P × (1 + R/100)ᵀ; CI = A − P | Interest compounded once a year. |
| 7 | Time and work (two people) | Days together = (a × b) ÷ (a + b) | When A alone takes a days and B alone takes b days. |
| 8 | Average | Sum of observations ÷ Number of observations | Averages, and finding a missing or replaced value. |
| 9 | Standard trig values | sin 30° = 1/2, sin 45° = 1/√2, sin 60° = √3/2; tan 45° = 1 | Heights and distances and value questions. |
| 10 | Rectangle and square | Rectangle: area = l × b, perimeter = 2(l + b); Square: area = a² | Area and perimeter questions. |
Worked Example: Discount and Profit
An item marked at ₹1,200 is sold at a 15% discount. It cost the seller ₹850.
- 1
Selling price
1,200 × (1 − 0.15) = ₹1,020.
- 2
Profit
1,020 − 850 = ₹170.
- 3
Profit %
170 ÷ 850 × 100 = 20%.
Questions from this exact syllabus. No signup.
Discount Is on Marked Price, Profit on Cost
Two different bases in one question is where most marks go. Discount % is worked on the marked price, and profit % on the cost price.
FAQs
Is CHSL maths easier than CGL?expand_more
Generally, yes. CHSL leans more on arithmetic, while CGL has more advanced algebra and geometry.
How is successive discount calculated?expand_more
Use net % = a + b + ab/100 with both discounts entered as negatives, for example 10% and 5% gives −14.5%.
Do I need trigonometry for CHSL?expand_more
Basic trigonometry ratios and standard values come up, but less than in CGL.
Next steps
Take a full SSC CHSL mock testThe whole Tier 1 syllabus in one timed, scored paper.