# Henslowe deals the cards

October 18, 2024 4:46 AM Subscribe

What happens when a 16thC manuscript page from the diary of Philip Henslowe (~1550 – 1616) is pushed in front of a math-wonk who a) recognises a problem in modulo arithmetic b) finds an error in the protocol? A card trick that stitches together Arts, STEM and edutainment.

Henslowe who he? An impressario and producer "

Henslowe who he? An impressario and producer "

*do you think it's funny?*", owner of The Rose playhouse, and a diarist of the Elizabethan drama scene in London. "Doctor's" handwriting that required a) transcription (

*tacke xij cards wth the knaue of clubes & laye them round licke a clocke*) then b) translation into modern English.

This is very neat--thanks! For comparison, there are tricks a little like this collected in

posted by Wobbuffet at 8:09 AM on October 18 [3 favorites]

*Newe Recreation, or the Mindes release and solacing*(1631). The first half of the book provides long lists of things the volunteer can choose and a standard method for figuring out which item was chosen, but the second half of the book has a bunch of ways to use arithmetic to get to, like, the same number that someone originally had in mind. I also know of*A Rich Cabinet with Variety of Inventions, Unlock'd and Open'd, for the Recreation of Ingenious Spirits*(1689), which has "Many Cards placed in divers ranks, to find which of these Cards any one hath thought"--which at a glance may be the same as this trick that appeared in*Le Manuel des sorciers*(1801) too. The second edition of*Le Manuel des sorciers*added a bunch of parlor games that led me to this stuff. Incidentally, the 'pre-programmed' tables in*Newe Recreation*were also a feature of recreational divination manuals like*The dodechedron of fortune; or, The exercise of a quick wit*(1613 but translated from French editions e.g. from 1556).posted by Wobbuffet at 8:09 AM on October 18 [3 favorites]

As a programmer, I always find the introduction of laypeople to modular arithmetic fun, as the usual experience for a programmer is the following:

Programmer in first grade: We learned about division, and that if you don't divide cleanly you get a remainder...and then we forget about them because we can divide to decimals and get the actual answer.

Programmer when they learn their first language: You remember those remainders from first grade? They're actually called the modulus, the way you get them is called the modulo function, and this is going to be a

Your neophyte programmer usually runs into modular arithmetic in one of two ways - either through the test for evenness (N % 2 == 0), or the emulation of an N-sided die ((Math.rand() % N) + 1). Which goes to show why the modulo is so useful as there's a lot of times where you want to know if a number is cleanly divided (this is how the classic FizzBuzz test works) or to break a big number down into a more usable smaller number.

posted by NoxAeternum at 12:42 PM on October 18

Programmer in first grade: We learned about division, and that if you don't divide cleanly you get a remainder...and then we forget about them because we can divide to decimals and get the actual answer.

Programmer when they learn their first language: You remember those remainders from first grade? They're actually called the modulus, the way you get them is called the modulo function, and this is going to be a

*very*useful tool for you.Your neophyte programmer usually runs into modular arithmetic in one of two ways - either through the test for evenness (N % 2 == 0), or the emulation of an N-sided die ((Math.rand() % N) + 1). Which goes to show why the modulo is so useful as there's a lot of times where you want to know if a number is cleanly divided (this is how the classic FizzBuzz test works) or to break a big number down into a more usable smaller number.

posted by NoxAeternum at 12:42 PM on October 18

This is a great "math magic" trick, if you can convert a number to base three in your head.

My Day 1 Lesson for my Algebra 2 class is on modulo arithmetic, joining chords on a circle with the "times table" to make a cardioid. Here's a Mathologer video where he explains it better than I can without a doc cam. We never return to modulo math, it's not useful for them in the course at all, but it accomplishes several things for a course introduction :

1) To show that math is about patterns and patterns can be beautiful.

2) To give my students practice making straight lines with rulers. You'd be surprised how many of them need it.

3) They don't have to spend Day 1 going over the syllabus.

4) I have student work to put up right away!

Anyway, fascinating article, thanks for posting!

posted by Ishbadiddle at 5:23 PM on October 18

My Day 1 Lesson for my Algebra 2 class is on modulo arithmetic, joining chords on a circle with the "times table" to make a cardioid. Here's a Mathologer video where he explains it better than I can without a doc cam. We never return to modulo math, it's not useful for them in the course at all, but it accomplishes several things for a course introduction :

1) To show that math is about patterns and patterns can be beautiful.

2) To give my students practice making straight lines with rulers. You'd be surprised how many of them need it.

3) They don't have to spend Day 1 going over the syllabus.

4) I have student work to put up right away!

Anyway, fascinating article, thanks for posting!

posted by Ishbadiddle at 5:23 PM on October 18

Given Beveridge's confusion about the historical meaning of the word "watch" (hint:

I wish people would check their work more before throwing up their hands.

posted by vitia at 1:45 AM on October 19

*not a thing on many people's wrists or necks or pockets or elsewhere in Shakespeare's time*), I'm glad he's up-front about the possible unreliability of the rest of his understanding of the text. The one-digit-off "It doesn't work" conclusion is hasty upon closer examination of the text: the trick works fine; it's Beveridge's interpretation that's broken.I wish people would check their work more before throwing up their hands.

posted by vitia at 1:45 AM on October 19

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posted by mittens at 6:41 AM on October 18