If you provide values for power and sample size, Minitab calculates the value of the maximum difference. If you provide values for power and maximum difference, Minitab calculates the value of the sample size.
For these two cases, Minitab uses an iterative algorithm with the power equation. At each iteration, Minitab evaluates the power for a trial sample size or trial difference, and stops when it reaches the values that you specify.
Target power and actual power
When Minitab calculates sample size, it might find that no integer value of sample size yields your target power. In such cases, Minitab displays the target value for power beside the actual power. The actual power is a value that corresponds to an integer sample size, and that is nearest to yet greater than the target value.