What is the square root of 81?

The square root of a number is a value that, when multiplied by itself, gives the original number. In this case, you are looking for a number that, when squared, equals 81.

When you take 9 and multiply it by itself (9 × 9), you get 81. This confirms that 9 is indeed the square root of 81. It is important to remember that the square root operation gives you the principal (non-negative) square root in most contexts unless specified otherwise.

Other numbers in the choices do not yield 81 when squared. For instance, 8 squared is 64, 10 squared is 100, and 11 squared is 121. Therefore, 9 is the only number from the provided options that correctly satisfies the definition of the square root in relation to 81.