Professor Hoffman was the pen-name of Angelo Lewis, a Victorian barrister whose book Modern Magic, published in 1876, is considered one of the most important and influential magic books of all time.
(I read about him recently in David Copperfield’s History of Magic, a stunning book he coauthored with psychologist Richard Wiseman and magician David Britland.)
Hoffman was also a puzzle enthusiast, and earlier today I set you ten puzzles taken from his 1893 classic book Puzzles Old & New. They are all classic lateral thinking problems. You may have heard some of them before, but I’m sure you can’t remember the solutions!
1. Required, to take one from nineteen and leave twenty. How is it to be done?
Solution Write nineteen in Roman numerals: XIX. Remove the I., and you have XX.
2. Place three sixes together so as to make seven.
Solution 6 6/6 [i.e 6 and six sixths]
3. How would you write in figures twelve thousand twelve hundred and twelve?
4. Out of six chalk or pencil strokes—thus, | | | | | | to make three, without striking out or rubbing out any.
Solution Add the necessary lines to complete the word “ three,” thus THREE.
5. You undertake to show another person something which you never saw before, which he never saw before, and which, after you both have seen it, no one else will ever see again. How is it to be done?
Solution The puzzle is solved by cracking a nut, showing the kernel, and then eating it.
6. You undertake to put something into a person’s left hand which he cannot possibly take in his right. How is it to be done?
Solution You place in the person’s left hand his own right elbow, which, obviously, he cannot take in his right hand.
7. You undertake to place a lighted candle in such a position that it shall be visible to every person save one; such person not to be blindfolded, or prevented from turning about in any manner he pleases. How is it to be done?
Solution You place the candlestick upon the head of the person who is not to see it.
8. A window in a certain house has recently been made twice its original size, but without increasing either its height or width. How can that be?
Solution The window was diamond-shaped. By enlarging it to a square its area is exactly doubled, without increasing either its height or width. A window shaped as an isosceles or right-angled triangle will equally answer the conditions of the puzzle.
9. A draper, dividing a piece of cloth into yard lengths, found that he cut off one yard per second. The piece of cloth was 60 yards in length. How long did it take him to cut up the whole?
Solution It took him 59seconds. Most people are apt to say 60, forgetting that the 59th cut separates the last two lengths, and that, therefore, a 60th is unnecessary.
10. How many hard-boiled eggs can a hungry man eat on an empty stomach?
Solution One only; for after eating one his stomach would be full
Thanks to Richard Wiseman for helping me with today’s column.
I set a puzzle here every two weeks on a Monday. I’m also the author of several books of popular science, most recently The Language Lover’s Puzzle Book, out in paperback in the UK, and just out in the US.
I’m always on the look-out for great puzzles. If you would like to suggest one, email me. I also give school talks about maths and puzzles (restrictions allowing). If your school is interested please get in touch.