## 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.

## Solution

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.

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 @EdmarkMLaw and Facebook. My email is learnfunfacts@gmail.com
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### 23 Responses to A Not-So-Straightforward Math Puzzle

1. Khansa Khan says:

wow 😀

Liked by 1 person

2. craftysurf says:

Holy Schnikes 🤪

Liked by 1 person

3. Lovely puzzle!! Enjoy and learnt both

Liked by 1 person

4. 3C Style says:

I enjoy puzzle like this. Thanks for sharing.

Liked by 1 person

5. 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

6. skullwoman says:

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

Liked by 1 person

7. paolsoren says:

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

Liked by 1 person

• It seems that many people nowadays only know up to X or less.

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

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9. This was awesome 👍

Liked by 1 person

10. LucciaGray says:

Clever!

Liked by 1 person

11. 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

• It would have worked if that’s the case (-3 + -1 + 10 = 6). However, the puzzle states: “And if fifty from forty be taken”. So, it’s 40 – 50 which is equal to -10.

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12. 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

• Good for you. Specialized mathematical fields like number theory and topology badly need people with that kind of mindset.

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