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# How do you find the LCM of 7 and 9?

Dec 15, 2016

63

#### Explanation:

Since the only number that $7$ and $9$ go into evenly is $63$ we must consider this simple step:

$7 \cdot 9 = 63$

A least common multiple is the smallest unit that both numbers can evenly be divided by. Since you can evenly divide $63$ by both $7$ and $9$ the following is true:

$63$ is the least common multiple of $7$ and $9$.

Aug 29, 2017

$L C M = 7 \times 9 = 63$

#### Explanation:

$7 \mathmr{and} 9$ have no common factor (apart from $1$).

Therefore the $L C M$ must contain the whole $7$ and the whole $9$.

$L C M = 7 \times 9 = 63$

This is clear if we write $7 \mathmr{and} 9$ as the product of the prime factors:

$\text{ } 7 = 7$
$\underline{\text{ "9= " } 3 \times 3}$

$L C M = 7 \times 3 \times 3 = 63$