Question: A museum curator discovers a binary-coded decimal (BCD) register in an early computer and finds a three-digit BCD number that represents a decimal number which is one less than a multiple of $11$. What is the largest such three-digit BCD number that follows this rule?

Tue, 21 Apr 2026 06:11:21 +0000

**A Museum Curator Uncovers a Cipher in Early Computing — What Hidden Number Reveals It’s One Less Than a Multiple of $11?** In a quiet moment behind museum walls, a curator exploring an early computing device made an intriguing discovery: a three-digit binary-coded decimal (BCD) register showing a number that, when converted to decimal, is one less than a multiple of $11$. This rare artifact blends history, cryptography, and number theory—offering more than just a riddle. It invites curiosity about how early computers encoded and processed digital information, and how such systems intersect with modern mathematical principles. Could this number hold a clue to forgotten systems, or reveal a pattern embedded in tech’s beginnings? --- ### Why This Discovery Matters Now