LCM( 5, 10 ) = 10
The formula for finding LCM is
$$ \text{LCM} (a, b) = \frac{ a \cdot b }{ \text{GCD}(a,b)} $$In this example we have: a = 5, b = 10 and GCD(5, 10) = 5.
$$ \text{LCM} (5, 10) = \frac{ 5 \cdot 10 }{ \text{GCD}(5,10)} = \frac{ 50 }{ 5 } = 10 $$