Costs
Country calendars mistakes, and the fixes that hold
Nine country calendars mistakes: assuming a Saturday and Sunday weekend, copying resolved dates for a rule-based closure, and treating a country as a timezone.
Section
Costs
Costs
Excel date serials and the 1900 and 1904 epochs: spreadsheet and API date handling
Excel date serials, the 1900 and 1904 epochs, text date traps, and spreadsheet and API tools that move dates without shifting or corrupting them.
Costs
The open-day formula with rest-day sets: five weekend conventions and cross-border spans
The open-day formula takes the rest-day set as an argument, with 2027 spans under five weekend conventions and the cross-border case for two ends.
Costs
Working hours holidays: a dated, sourced directory
Working hours holidays in 2027: the closure dates that move deadlines, who publishes each one, and how to check the list your filing depends on.
Costs
Working Days Per Year Examples: Fiscal Baseline Checks
Working days per year examples: build a fiscal-span weekday baseline from monthly counts, subtract the federal holiday list for three spans, and reverse-check a reported total.
Costs
Days between dates in Excel: subtraction, times, DATEDIF and NETWORKDAYS
Excel formulas for days between dates: subtraction and inclusive counts, times in cells, DATEDIF units, NETWORKDAYS and WORKDAY, and what the sheet cannot decide.
Costs
Subtract business days API: direction, request fields, and response shape
How to design a subtract business days API: putting direction in its own field, the request fields it must carry, and what a response should echo back.
Costs
Workday counts for a month: why length and starting weekday decide the total
Working days per month is 20 to 23 weekdays, decided by month length and start weekday: the rule behind it, a worked year, and where the count misleads.