Chapter 1 · Question 2

Find the HCF of 135135 and 225225 using Euclid's division algorithm.

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Q2

Find the HCF of 135135 and 225225 using Euclid's division algorithm.

Answer Revealed
Direct Answer:
Using Euclid's algorithm: 225=135×1+90225=135\times1+90, 135=90×1+45135=90\times1+45, 90=45×2+090=45\times2+0. Therefore, HCF =45=45.

Simple Explanation

Keep dividing and carrying the remainder forward. The last non-zero remainder is 4545, so that is the HCF.

Exam-Ready Structure

Apply Euclid's algorithm stepwise: 225=135(1)+90225=135(1)+90; 135=90(1)+45135=90(1)+45; 90=45(2)+090=45(2)+0. Since the remainder has become zero, the divisor at this stage is the HCF. Hence HCF(135,225)=45\operatorname{HCF}(135,225)=45.

Key Points

  • Using Euclid's algorithm: 225=135×1+90225=135\times1+90, 135=90×1+45135=90\times1+45, 90=45×2+090=45\times2+0.
  • Use the NCERT formula or theorem carefully.
  • Write units and final conclusion where applicable.