Henry Ernest Dudeney/Modern Puzzles/100 - Odds and Evens
Jump to navigation
Jump to search
Modern Puzzles by Henry Ernest Dudeney: $100$
- Odds and Evens
- Here is a little parlour trick, the explanation of which is quite easy.
- Ask a friend to take an even number of coins in one hand and an odd number in the other.
- You then undertake to tell him which hand holds the odd and which the even.
- Tell him to multiply the number in the right hand by $7$ and the number in the left by $6$,
- add the two products together, and tell you the result.
- You can then immediately give him the required answer.
- How are you to do it?
- In practice, after he had given me the result, I should say,
- "Let us add your age, now deduct the day of the month," and so on --
- a lot of absurd apparent calculations merely devised for his mystification,
- for you already know the answer.
Click here for solution
Sources
- 1926: Henry Ernest Dudeney: Modern Puzzles ... (previous) ... (next): Arithmetical and Algebraical Problems: Various Arithmetical and Algebraical Problems: $100$. -- Odds and Evens