Question

Find the square of $85$.

Answer 1

Find the square of the given number

We can find the square of $85$ by applying the identity ${(a-b)}^2=a^2-2ab+b^2$

Now, $85$ can be written as $100-15$.

On applying the identity, we get,

$$\begin{gathered} {\left(85\right)}^2 \\ ={(100-15)}^2 \\ ={\left(100\right)}^2-2\left(100\right)\left(15\right)+{\left(15\right)}^2 \\ =10000-3000+225 \\ =7225 \end{gathered}$$
Hence, using an identity, the square of $85$ is $7225$.