The last day of a century cannot be

Concept

• The last day of a century refers to 31st December of a year ending in '00' (e.g., 1700, 1800, 1900, 2000).
• Century years are leap years only if divisible by 400; otherwise, they are common (non-leap) years.
• Using odd-day analysis (number of days modulo 7) over centuries, it can be shown that the last day of a century can only fall on Sunday, Monday, or Friday in the Gregorian calendar; equivalently, it cannot be Tuesday, Thursday, or Saturday.

Illustrations

• 31 Dec 1900 → Monday
• 31 Dec 2000 → Sunday

Final Answer
The last day of a century cannot be Tuesday.