Question

LCM and HCF of 21,28,36,45

Answer 1

Step-by-step explanation:

by prime factorization

$$\begin{lgathered}21 = 3 \times 7 \\ 28 = 2 \times 2 \times 7 \\ 36 = 2 \times 2 \times 3 \times 3 \\ 45 = 3 \times 3 \times 5\end{lgathered}$$

now hcf is the common one

therefore hcf = 1 (as there are no common factor )

lcm =

$$\begin{lgathered}2 \times 2 \times 3 \times 3 \times 5 \times 7 \\ = 1260\end{lgathered}$$

hope it helps you

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Answer 2

Step-by-step explanation:

21 = 3 × 7

28 = 2 × 2 × 7 = 2^2 × 7

36 = 2 × 2 × 3 × 3 = 2^2 × 3^2

45 = 5 × 3 × 3 = 5 × 3^2

HCF = product of smallest power of each common prime factor in the numbers = 1

LCM = product of greatest power of each prime factor involved in the numbers =

2^2 × 3^2 × 5 × 7 = 1260