Answer
$81 = 3\cdot 3\cdot 3\cdot 3$
Work Step by Step
The $\textit{prime factorization}$ of a number is obtained by writing the number as a product of primes.
To determine the prime factorization of $81$ we write the number as a product of factors and continue the process until all factors are prime numbers.
We start by writing $81$ as a product of two numbers:
$81=3\cdot 27$.
The number $3$ is prime, but $27$ is not. So we write $27=3\cdot 9$:
$81=3\cdot 3\cdot 9$.
As $9$ is not a prime number we write: $9=3\cdot 3$ and we have:
$81=3\cdot 3\cdot 3\cdot 3$.
Now each factor is a prime number, therefore the prime factorization of $81$ is $3\cdot 3\cdot 3\cdot 3$.
