LCM( 256, 64 ) = 256
The formula for finding LCM is
$$ \text{LCM} (a, b) = \frac{ a \cdot b }{ \text{GCD}(a,b)} $$In this example we have: a = 256, b = 64 and GCD(256, 64) = 64.
$$ \text{LCM} (256, 64) = \frac{ 256 \cdot 64 }{ \text{GCD}(256,64)} = \frac{ 16384 }{ 64 } = 256 $$