To compare \(\sqrt{81}\) and \(\sqrt{88}\), we can first compute the square roots:
\[ \sqrt{81} = 9 \]
Now, we can estimate \(\sqrt{88}\). Knowing that \(88\) is close to \(81\) and \(100\), we can find:
\[ \sqrt{88} \approx 9.38 \]
(We can confirm this by noting that \(9.3^2 = 86.49\) and \(9.4^2 = 88.36\), which implies that \(9.3 < \sqrt{88} < 9.4\)).
Thus, we have:
\[ \sqrt{81} = 9 < \sqrt{88} \approx 9.38 \]
So, we have the inequality:
\[ \sqrt{81} < \sqrt{88} \]
The complete statement is:
\[ \sqrt{81} < \sqrt{88} \]
Therefore, the answer is:
\(<\)