Henry Ernest Dudeney/Puzzles and Curious Problems/358 - Simple Addition/Solution

Puzzles and Curious Problems by Henry Ernest Dudeney: $358$

Simple Addition

Can you show that four added to six will make eleven?

Solution

Express $4$ and $6$ in Roman numerals, perhaps using matches: $\text {IV}$ and $\text {VI}$.

Then turn $\text {IV}$ upside down and put it below $\text {VI}$, and see it makes $\text {XI}$.

This is $11$ in Roman numerals.

Sources

• 1932: Henry Ernest Dudeney: Puzzles and Curious Problems ... (previous) ... (next): Solutions: $358$. -- Simple Addition
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Answers: $515$. Simple Addition