CDS Mathematics · Teaching notes
Sequence and Series — CDS Elementary Mathematics
Sequence and Series has 19 past-year questions in CDS Elementary Mathematics, in 14 of the twenty-one sittings from 2016 (II) to 2026 (II). Ten sum a progression or a special series, and nine ask about the arithmetic, geometric and harmonic means of two numbers; the only two HARD items are telescoping sums. The first page covers progressions and special sums, the second the three means.
Every subtopic, worked example, formula and trap in one printable document — answers shown, ready to share.
Subtopic notes
Formula & revision sheet
3 formulas · 3 gotchas across all subtopics — the exam-eve cheat-sheet
Formula & revision sheet
3 formulas · 3 gotchas across all subtopics — the exam-eve cheat-sheet
Watch out for (2)
- Stop at the last positive term→ Sums of APs and GPs
- Count the surviving ends→ Telescoping sums
Formulas (1)
Watch out for (1)
- The GM squared, not the GM, is the product→ AM, GM and HM of two numbers
PYQ weightage by concept
3 concepts · 19 PYQs — where the marks actually sit, so you know what to drill first
PYQ weightage by concept
3 concepts · 19 PYQs — where the marks actually sit, so you know what to drill first
| Concept | PYQs | Share |
|---|---|---|
| Sums of APs and GPs | 7 | 37% |
| Telescoping sums | 3 | 16% |
Test yourself on a real paper
Sit a past CDS paper, timed and marked the way the exam marks it. You see your score and every answer the moment you finish. Free to start.