LCM( 20, 2 ) = 20
The formula for finding LCM is
$$ \text{LCM} (a, b) = \frac{ a \cdot b }{ \text{GCD}(a,b)} $$In this example we have: a = 20, b = 2 and GCD(20, 2) = 2.
$$ \text{LCM} (20, 2) = \frac{ 20 \cdot 2 }{ \text{GCD}(20,2)} = \frac{ 40 }{ 2 } = 20 $$