What is the next number in the series?
$$\text{Series: }9,27,81,243,\dots$$

Let's analyze the pattern of the given series:
The consecutive terms are multiplied by a constant factor of $3$:

$$9\times 3=27$$

$$27\times 3=81$$

$$81\times 3=243$$

Following the same logic, the next term will be:

$$243\times 3=729$$

Alternatively, these are consecutive powers of $3$ starting from $3^2$:

$$3^2=9$$

$$3^3=27$$

$$3^4=81$$

$$3^5=243$$

$$3^6=729$$