The base division
Forward direction: annual salary divided by (hours per week times weeks per year). The default is 40 times 52, or 2,080 hours, the standard full-time work-year figure. Reverse direction: multiply the hourly rate by the same product. All output rows, hourly, weekly, biweekly, monthly, and annual, derive from the same two inputs, so changing weeks worked recalculates every row consistently.