LCM( 210, 315 ) = 630
The formula for finding LCM is
$$ \text{LCM} (a, b) = \frac{ a \cdot b }{ \text{GCD}(a,b)} $$In this example we have: a = 210, b = 315 and GCD(210, 315) = 105.
$$ \text{LCM} (210, 315) = \frac{ 210 \cdot 315 }{ \text{GCD}(210,315)} = \frac{ 66150 }{ 105 } = 630 $$