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CTET 1 Mar 2026 Paper 1, Question 46

Topic: Pedagogy of mathematics

Q46

A primary class mathematics teacher gave his students the following problem to solve :
“If the price of one toy car is ₹ 50, then what would be the cost of 25 such toy cars ?”
One of the students responded, “Ten cars will be ₹ 500; twenty cars will be ₹ 1,000; five cars will be ₹ 250; so the total cost is ₹ 1,250.”
What are the heuristics used by the student in the above algorithm ?

  1. (1) The commutative law of addition
  2. (2) Decomposition and associative law
  3. (3) Decomposition and repeated groupingsCorrect answer
  4. (4) The associative law of multipliation

Solution.

CBSE answer: (3)

Answer: (3) Decomposition and repeated groupings

  1. The student breaks 25 into convenient parts, 25=20+525 = 20 + 5 (decomposition).
  2. Groups of ten cars are built and doubled: 10 cars ₹ 500, 20 cars ₹ 1,000, and 5 cars as half of ten, ₹ 250 (repeated grouping).
  3. Partial costs are then added: 1000+250=12501000 + 250 = 1250.

Trap: no rearranging of addends or factors is shown, so commutative or associative law is not the strategy.