Question

Using the prime factorisation, find the factors of $81$and also its square root.

Answer 1

To find the square root of $81$we will factorise it first

Here we have to find the prime factors of $81$.

Divide $81$by $3$;

$81÷3=27$

Divide $27$by $3$

$27÷3=9$

Divide $9$by $3$

$9÷3=3$

Divide $3$by $3$

$3÷3=1$

By prime factorisation, we know:

$81=3x3x3x3$

Factorization of $81$

So prime factorization of$81=3x3x3x3$ which can be written as $(3x3)X(3x3)$

Pairing the numbers to get the perfect squares we get;

$81=9x9=9^2$

Hence The square root of $81$is $9$