LCM( 9, 18 ) = 18
The formula for finding LCM is
$$ \text{LCM} (a, b) = \frac{ a \cdot b }{ \text{GCD}(a,b)} $$In this example we have: a = 9, b = 18 and GCD(9, 18) = 9.
$$ \text{LCM} (9, 18) = \frac{ 9 \cdot 18 }{ \text{GCD}(9,18)} = \frac{ 162 }{ 9 } = 18 $$