SSC CGL Quant · Study & Practice

Simple & Compound Interest

AreaArithmetic DifficultyEasy–Moderate SSC weightage3–5 questions

Simple interest grows by a fixed amount each year (interest on the principal only); compound interest grows on the running balance, so it snowballs. Two relations carry most SSC marks: SI = PRT/100, and Amount under CI = P(1 + R/100)^T. Knowing the difference between CI and SI for 2 years (= P(R/100)^2) and for 3 years lets you jump straight to the answer. Percentage fluency from the percentage chapter pays off directly here.

Topics

1 Simple Interest 4 worked · 5 practice · 8-Q test Start → 2 Compound Interest 4 worked · 5 practice · 8-Q test Start → 3 SI vs CI 4 worked · 5 practice · 8-Q test Start → 4 Growth & Depreciation 4 worked · 5 practice · 8-Q test Start →

⚡ SSC shortcuts & speed methods

The fastest ways to crack this chapter under time pressure — the techniques that separate a 95+ percentiler from the rest.

  • A sum becomes n times in t years at SI -> (n-1) = RT/100.
  • CI multiplier per year = (1 + R/100); chain it for T years.
  • CI - SI (2 years) = P(R/100)^2.
  • Half-yearly: rate R/2, periods 2T. Quarterly: R/4, 4T.
  • Depreciation uses (1 - R/100)^T.

⚠️ Common mistakes & traps

SSC is designed so that careless errors here cost you marks. Internalise each trap before the exam.

  • Applying CI yearly when the problem says half-yearly (halve the rate, double periods).
  • Forgetting CI = Amount - Principal (not the amount itself).
  • Using SI formula where compounding is intended.
  • Mixing up growth (+) and depreciation (-) factors.

📈 SSC exam insight & PYQ analysis

SSC reliably asks the 2-year CI-SI difference (find P or R), half-yearly CI, and depreciation. Treat CI as successive percentage changes for speed.

🎴 Flashcards — instant recall

Tap a card to reveal the answer. Drill these until they are automatic.

SI formula?Tap to reveal
PRT/100
CI amount formula?Tap to reveal
P(1 + R/100)^T
CI-SI for 2 years?Tap to reveal
P(R/100)^2
10% CI for 2 years multiplier?Tap to reveal
1.21
Half-yearly at 10% for 1 year uses?Tap to reveal
5% for 2 periods

📌 Quick revision

SI is linear (PRT/100); CI compounds as P(1+R/100)^T. Use the 2-year difference P(R/100)^2 to find P or R fast, chain yearly multipliers for growth, and (1-R/100)^T for depreciation. Half-yearly halves the rate and doubles the periods.

Chapter test

📝 Simple & Compound Interest — Chapter Test
25 fresh questions · timed · full solutions
Start chapter test →
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🏆 Vidaara SSC success checklist

You have truly mastered Simple & Compound Interest when you can tick every box below.

  • Recall every formula in this chapter without looking them up
  • Solve each topic’s practice set with at least 80% accuracy
  • Use the chapter shortcuts to cut your solving time in half
  • Spot and avoid every common trap listed above
  • Score 80%+ on the timed chapter test

📋 Chapter mastery scorecard

Track where you stand. Aim for the target before moving to the next chapter.

Skill checkpointTarget
Concept theory & formulas understood100%
Topic practice sets attempted (4 topics)4/4
Best topic-test score— → 80%+
Chapter test score— → 80%+
Flashcards drilled to instant recall5 cards