With Coefficients

When you multiply powers, the exponents of the same base add. The numbers in front are called coefficients. Coefficients multiply.

$$5{x}^{2}\cdot 3{x}^{4} = 15{x}^{6}$$

$5\cdot 3 = 15$ and $2+4 = 6$. An $x$ with no exponent counts as ${x}^{1}$, so ${x}^{2}\cdot x = {x}^{3}$.