What years can be inter changer?

Interchangeable years typically refer to those that share the same calendar structure, meaning they start and end on the same day of the week and have the same leap year status. For example, 2021 and 2032 can be interchanged because both are common years that start on a Friday. However, to determine specific interchangeable years, one would generally look at the cycle of the Gregorian calendar, where years can repeat their structure every 28 years, though exceptions may exist due to leap years.