The expression $9^2$ means 9 raised to the power of 2, or 9 multiplied by itself:

$9^2 = 9 \times 9 = 81$

Thus, $9^2 = 81$.

Would you like more details or have any questions?

Here are five related questions to explore:

1. What is $12^2$?
2. How do you simplify $10^2 + 9^2$?
3. What is the square root of 81?
4. What is the value of $9^3$?
5. How do you express $x^2$ for $x = 9$?

Tip: Squaring a number means multiplying the number by itself.