<?xml version="1.0" encoding="UTF-8" standalone="yes"?><oembed><version><![CDATA[1.0]]></version><provider_name><![CDATA[justpuzzles]]></provider_name><provider_url><![CDATA[https://justpuzzles.wordpress.com]]></provider_url><author_name><![CDATA[Teun Spaans]]></author_name><author_url><![CDATA[https://justpuzzles.wordpress.com/author/teunspaans/]]></author_url><title><![CDATA[Alcuins 100-problems]]></title><type><![CDATA[link]]></type><html><![CDATA[<p>In this blog I mentioned  Alcuin of Yorks puzzle collection <i>Propositiones alcuini doctoris caroli magni imperatoris ad acuendos juvenes</i> several times. It  was possibly published around 800, and contained 53 problems.</p>
<p>A number of these problems are what we now would term &#8220;1 equation with 1 unknown&#8221;. Among these are a number which expand on a number, performs a number of calculation operations, and give the answer.<br />
Example:<br />
<strong>Nr 2</strong>: propositio de viro ambulante in via<br />
A certain  man walking  in the street saw other men coming towards him, and he said  to them: &#8220;O  that there  were so  many [more]  of you as you are [now]; and  then half  of half  of this [were added]; and then half of this number [were  added], and  again, a  half of [this] half.  Then, along with me, you  would number 100 [men].&#8221;  Let him say, he who wishes, How many men were first seen by the man?.&#8221; How many men were first seen by the man?</p>
<p>Alcuin gives the solution:<br />
Those who  were first  seen by the man were 36 in number; double this would be 72. A  half of  half of this is 18, and a half of this number makes 9. Therefore, say  this:   72 and  18 makes  90.   Adding 9  to this makes 99. Include the speaker and you shall have 100.</p>
<p>To see how this can be solved with elementary algebra, let&#8217;s call the number of men x.<br />
&#8211; Then that there  were so  many [more]  of you as you are [now]: x+x=2x<br />
&#8211; and  then half  of half  of this [were added]: 2x + 0,5x=2,5x<br />
&#8211; and then half of this number [were  added]: 2,5x + 0,25x=2,75x<br />
&#8211; and adding 1 makes 100.<br />
So 2,75x +1 = 100<br />
2,75x=99<br />
11/4x=99<br />
1/4x=9<br />
x=36</p>
<p><strong>Nr 3</strong>: propositio de duobus proficiscentibus<br />
Two men were walking in the street when they noticed some storks. They asked each other, &#8220;How many are there?&#8221; Discussing the matter, they said: &#8220;If [the storks] were doubled, then taken three times, and then half of the third [were taken] and with two more added, there would be 100.&#8221; How many [storks] were first seen by the men?</p>
<p>This one leads itself for a second way of solving, working backwards:<br />
&#8211; with two more added: 100/2=98<br />
&#8211;  doubled, then taken three times, and then half of the third taken: like in the previous one, the main problem is in figuring out what Alcuin actually meant.</p>
<p><strong>Nr 4</strong>: propositio de homine et equis<br />
A certain man saw some horses grazing in a field and said longingly: &#8220;O that you were mine, and that you were double in number, and then a half of half of this [were added]. Surely, I might boast about 100 horses.&#8221;<br />
How many horses did the man originally see grazing?</p>
<p><strong>nr 36</strong>: propositio de salutatione cujusdam senis ad puerum<br />
A certain old man greeted a boy, saying to him: &#8220;May you live, boy, may you live for as long as you have [already] lived, and then another equal<br />
Recreational problems Alcuin 5 Albrecht Heeffer amount of time, and then three times as much. And may God grant you one of my years, and you shall live to be 100.&#8221; How many years old was the boy at that time?</p>
<p>Nr 40: propositio de homine et ovibus in monte pascentibus<br />
A certain man saw from a mountain some sheep grazing and said, &#8220;O that I could have so many, and then just as many more, and then half of half of this [added], and then another half of this half. Then I, as the 100th [member], might head back to my home together with them.&#8221; How many sheep did the man see grazing?</p>
<p>Nr 45: propositio de salutatione pueri ad patrem<br />
A certain boy addressed his father, saying, &#8220;Greetings, father!&#8221; The father responded, &#8220;May you fare well, my son, and may you live three times twice your years. Then, adding one of my own years, you will live to be 100.&#8221; How many years was the boy at the time?Nr 46: Propositio Recreational problems Alcuin 6 Albrecht Heeffer A dove sitting in a tree saw some other doves flying and said to them, &#8220;O that you were doubled, and then tripled. Then, along with me, you would number 100.&#8221; How many doves were initially flying?</p>
<p>nr 48: propositio de homine qui obviavit scholaribus<br />
A certain man met some students and asked them, &#8220;How many of you are there in school?&#8221; One of [the students] responded to him: &#8220;I do not want<br />
to tell you [except as follows]: double the number of us, then triple that number; then, divide that number into four parts. If you add me to one of the fourths, there will be 100.&#8221; How many [students] first met the man?</p>
<p>I do not intend to publish the solutions of these problems.</p>
<p>There will be more on this topic in my upcoming <a href="https://justpuzzles.wordpress.com/e-books/">e-book</a> on number puzzles.</p>
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