Henry Ernest Dudeney/Puzzles and Curious Problems/359 - Queer Arithmetic/Solution

Puzzles and Curious Problems by Henry Ernest Dudeney: $359$

Queer Arithmetic

Can you take away seven-tenths from five so that exactly four remains?

Solution

Arrange $10$ matches to spell the number $\text {FIVE}$.

Then remove the $7$ of those $10$ that are used to form the $\text F$ and the $\text E$.

This leaves us with the $3$ matches remaining to form the $\text{IV}$, which is $4$ in Roman numerals.

Sources

• 1932: Henry Ernest Dudeney: Puzzles and Curious Problems ... (previous) ... (next): Solutions: $359$. -- Queer Arithmetic
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Answers: $509$. Queer Arithmetic