A data processing apparatus has a processing circuitry for performing a floating-point square root operation on a radicand value R to generate a result value. The processing circuitry has first square root processing circuitry for processing radicand values R which are not an exact power of two and second square root processing circuitry for processing radicand values which are an exact power of 2. Power-of-two detection circuitry detects whether the radicand value is an exact power of two and selects the output of the first or second square root processing circuitry as appropriate. This allows the result to be generated in fewer processing cycles when the radicand is a power of 2.