LCM( 5, 9 ) = 45
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 = 9 and GCD(5, 9) = 1.
$$ \text{LCM} (5, 9) = \frac{ 5 \cdot 9 }{ \text{GCD}(5,9)} = \frac{ 45 }{ 1 } = 45 $$