LCM( 5, 8 ) = 40
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 = 8 and GCD(5, 8) = 1.
$$ \text{LCM} (5, 8) = \frac{ 5 \cdot 8 }{ \text{GCD}(5,8)} = \frac{ 40 }{ 1 } = 40 $$