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Date and Time Calculation

Add or subtract calendar time and clock time from a date.

Start with a date and an optional time, choose add or subtract, then enter any mix of years, months, weeks, days, hours, minutes, and seconds. Month and year shifts clamp to the last valid day when needed, so January 31 plus one month becomes February 28 or 29. Hours, minutes, and seconds carry over into the next or previous day.