NCERT Mathematics, Class 11, textbook pages 100–125

How to help your child with Class 11 Maths Chapter 6, Permutations and Combinations, at home

Counting principle, arrangements and selections, explained for parents: a 45-minute study session, a quick challenge, a 5-day plan and the mistakes to watch for.

⁷P₃ = 210 (order matters)⁷C₃ = 35 (order doesn’t)nCr = n!/(r!(n−r)!)

NCERT Class 11 Maths Chapter 6 Permutations and Combinations: what it teaches

Your teen counts systematically with the fundamental principle of counting, factorials, permutations (order matters) and combinations (order doesn’t), and solves word and letter-arrangement problems.

Why it matters later. Counting is the basis of the binomial theorem (Chapter 7) and probability.

See it: this chapter in pictures

3 shirts × 4 trousers= 12 outfitscounting principle
Multiply the choices.
BOOK: 4 letters, O twice4!/2! = 12divide by repeats
Divide by repeated factorials.
captain, vice, treasurer from 7⁷P₃ = 210team of 3: ⁷C₃ = 35
Roles make order matter.

You need

  • letter cards
  • a calculator

Tonight’s 45 minutes

  1. Outfits: 3 shirts and 4 trousers give how many combinations? (12)
  2. Arrange the letters of ‘CAT’ (6) and ‘BOOK’ (12).
  3. Choose a team of 3 from 7 (35) vs a captain, vice and treasurer (210).
  4. Decide in each problem: does order matter?

Words to use

  • factorial
  • permutation
  • combination
  • nPr
  • nCr
  • counting principle

Watch for

  • Using permutations when order doesn’t matter. Ask: would swapping two choices give a different outcome?
  • Forgetting repeated letters. Divide by factorials of repeats.

What it sounds like at home

A short example of the conversation. Your words will differ; the questions are what matter.

YouTeam of 3 from 7: order matters?

Your childNo: ⁷C₃ = 35.

A game for this week: Order matters?

  1. Read situation cards.
  2. Decide permutation or combination.
  3. Calculate.
  4. Points for both.

A 5-day plan, 45 minutes a day

  1. Day 1Explain-back.
  2. Day 2Worked examples.
  3. Day 3Practice set.
  4. Day 4Real-life problem.
  5. Day 5Mixed quiz.

Everyday moments to practise

  • Passwords and PINs.
  • Team selection.
  • Seating plans.
  • Lottery odds.

Quick check

Ask these at the end of the week. Tap to see the answer.

5!?

120.

⁷C₃?

35.

Arrangements of BOOK?

12.

Ready for the next chapter when your child…

  • Uses the counting principle.
  • Distinguishes nPr and nCr.
  • Handles repeated objects.

Activities, wording and illustrations are Mathify Kids’ own, following the topics of NCERT’s Mathematics (Class 11). See the full Class 11 parent guide for every chapter.

Questions parents ask

Difference between permutation and combination?

Permutations count arrangements (order matters); combinations count selections.

What is 0!?

1.

Formula for nCr?

n! / (r!(n − r)!).