A Not-So-Straightforward Math Puzzle


The following is a puzzle from Rational Amusements from Winter Evenings (1821) by John Jackson:

If from six ye take nine, and from nine ye take ten
(Ye youths, now the mystery explain;)
And if fifty from forty be taken, there then,
Shall just half a dozen remain.

Can you figure out what’s going on? This is not an easy one so you may take your time.


Have you figured it out? Simple arithmetic alone won’t solve this. You must apply your knowledge of math, Roman numerals, and wordplay to crack this puzzle.

Here’s the solution:

SIX – IX = S
    IX – X = I
   XL – L = X

There are more puzzles similar to this in the abovementioned book. If you like this kind of puzzle, then let me know and I’ll post a few more of them.

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My name Edmark M. Law. I work as a freelance writer, mainly writing about science and mathematics. I am an ardent hobbyist. I like to read, solve puzzles, play chess, make origami and play basketball. In addition, I dabble in magic, particularly card magic and other sleight-of-hand type magic. I live in Hong Kong. You can find me on Twitter` and Facebook. My email is edmarklaw@learnfunfacts.com

24 thoughts on “A Not-So-Straightforward Math Puzzle

  1. holy shit… I am bad at math, so it’s said at least, but I figured it out in one go??? I got into some severe trouble with my math teacher earlier, when I figured out the most difficult question on the sheet in a test, but left all other easy questions unanswered, due to no time, but she would not believe it. She rather thought I was about to anger her… Well, I still would think I am the most stupid pupil of all and of all time. I just had some other info, did I ? Who knows.. . I don’t even know myself. ☻♦
    I always read words in other/different meanings and take it quite far, so there is always a solution at hand…

    Liked by 1 person

  2. Yes, but there is another solution. From 6 take 9, you’re left with -3. From 9 take 10, you’re left with -1. So we have -4. From 50 take 40, leaves 10 … 10-4=6 and 6 is half a dozen.

    Liked by 1 person

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