Question
Using prime factorization, find the $HCF$ and $LCM$ of:
$21, 28, 36, 45$.
$21, 28, 36, 45$.
✓
Answer
$ 21=3 \times 7 $
$ 28=2 \times 2 \times 7=2^2 \times 7 $
$ 36=2 \times 2 \times 3 \times 3=2^2 \times 3^2 $
$ 45=3 \times 3 \times 5=3^2 \times 5 $
$ \operatorname{HCF}(21,28,36,45)=1 $
$ \operatorname{LCM}(21,28,36,45)=2^2 \times 3^2 \times 5 \times 7=1260$
$ 28=2 \times 2 \times 7=2^2 \times 7 $
$ 36=2 \times 2 \times 3 \times 3=2^2 \times 3^2 $
$ 45=3 \times 3 \times 5=3^2 \times 5 $
$ \operatorname{HCF}(21,28,36,45)=1 $
$ \operatorname{LCM}(21,28,36,45)=2^2 \times 3^2 \times 5 \times 7=1260$
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