LCM( 3, 6 ) = 6
The formula for finding LCM is
$$ \text{LCM} (a, b) = \frac{ a \cdot b }{ \text{GCD}(a,b)} $$In this example we have: a = 3, b = 6 and GCD(3, 6) = 3.
$$ \text{LCM} (3, 6) = \frac{ 3 \cdot 6 }{ \text{GCD}(3,6)} = \frac{ 18 }{ 3 } = 6 $$