NCERT Exemplar Solutions
Class 6 - Mathematics - Unit 1: Number System - Multiple Choice QuestionsQuestion 37
Class 6 - Mathematics - Unit 1: Number System - Multiple Choice Questions
Question. 37
LCM of 10, 15 and 20 is
(A)
30
(B)
60
(C)
90
(D)
180
Detailed Answer with Explanation:
Step 1: Write prime factors.
\(10 = 2 \times 5\)
\(15 = 3 \times 5\)
\(20 = 2 \times 2 \times 5 = 2^2 \times 5\)
Step 2: For LCM, take each prime with the highest power.
From the lists above:
Prime \(2\): highest power is \(2^2\).
Prime \(3\): highest power is \(3^1\).
Prime \(5\): highest power is \(5^1\).
Step 3: Multiply these together.
\(2^2 = 4\)
\(4 \times 3 = 12\)
\(12 \times 5 = 60\)
Answer: LCM \(= 60\). So the correct option is B.