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.


About Edmark M. Law

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. I blog at learnfunfacts.com. You can find me on Twitter @EdmarkLaw and Facebook. My email is edmarklaw@learnfunfacts.com
This entry was posted in Language, Mathematics, Poetry, Puzzles and tagged , , , , . Bookmark the permalink.

24 Responses to A Not-So-Straightforward Math Puzzle

  1. Pingback: A Not-So-Straightforward Math Puzzle — Learn Fun Facts – Wacks Formula – Math Shortcuts

  2. Pingback: Another Not-So-Straightforward Math Puzzle | Learn Fun Facts

  3. emmitsomo says:

    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

  4. Kanti Burns says:

    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

  5. My partner liked the challenge, & enjoyed playing round with roman numerals. He would be happy for you to post more!

    Liked by 1 person

  6. paolsoren says:

    It is so good to know that somebody remembers Roman numerals.

    Liked by 1 person

  7. skullwoman says:

    Nice brain teaser to try to solve over morning coffee. Thank you!

    Liked by 2 people

  8. Jack Shalom says:

    Nice puzzle. I tried working with Roman numerals, but didn’t get the trick of using them in conjunction with actual words. That was very sneaky!

    Liked by 1 person

  9. 3C Style says:

    I enjoy puzzle like this. Thanks for sharing.

    Liked by 1 person

  10. Lovely puzzle!! Enjoy and learnt both

    Liked by 1 person

  11. craftysurf says:

    Holy Schnikes 🤪

    Liked by 1 person

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