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SAMDOB – mess up the order of operations

While I’m on strike, I’m catching up on stuff I’ve made but never posted about here.

At the Talking Maths in Public conference last August, I was talking with Katie Steckles and Kevin Houston about the order of operations. I think that another one of those ambiguously-written sums had gone round Twitter again. I said it would be good to have a tool where you can write an expression, then change the order of operations and see what happens.

So, on the way home, I wrote one! I’ve called it SAMDOB, which is an anagram of BODMAS.

Screenshot of SAMDOB, showing the order of operations BO(DM)(AS) on the expression 2*3/3*2+2, which evaluates to 6
Screenshot showing how with the order of operations BOMD(AS), the expression evaluates to 3
Screenshot showing how with the order of operations BO(AS)(MD), the expression evaluates to 8.

Please have a play with it. I can imagine that this could be useful to people teaching the order of operations in real life. Let me know if you have any suggestions for improvements.

The code is on GitHub.

A paper version of the Seven Triples puzzle

Last year I wrote about a 3D-printed puzzle I’d designed, called Seven Triples.

At work we want to use this puzzle during an A-Level enrichment day, which means we need about twenty copies of it. I 3D-printed four copies over the course of a couple of weeks, in amongst other jobs, and I don’t have the patience to do any more. So, I’ve made a 2D version that we can print and cut out much more quickly.

Triangles arranged in rows. Each triangle is filled with one of seven patterns. There are white, yellow and magenta triangles.

Carnival of Maths 178

The next issue of the Carnival of Mathematics, rounding up blog posts from the month of January, is now online at Storm Bear World.

Screenshot of Carnival 178

The Carnival rounds up maths blog posts from all over the internet, including some from our own Aperiodical. See our Carnival of Mathematics page for more information.

Geogebra to Cake in Five Steps

Flower design using Reflect Object in Circle tool in Geogebra
Tessellated squares design using Reflect Object in Circle tool in Geogebra

In the Aperiodical’s Big Internet Math-Off 2019, Becky Warren posted an entry about Geogebra’s ‘reflect object in circle’ tool (it’s the second article in the post). I enjoyed playing with the tool and, after making a few colourful designs, it occurred to me that one of them would make a great cake for the MathsJam bake-off. It would only work if the curves were accurate; sadly this would be beyond my drawing abilities, and definitely beyond my piping abilities. But with some help from 3D printing I thought I might be able to manage it.

Here are the steps I used to transfer the design to a cake.

Carnival of Maths 176/177

The next issue of the Carnival of Mathematics, rounding up blog posts from the months of November and December, is now online at Ganit Charcha.

The Carnival rounds up maths blog posts from all over the internet, including some from our own Aperiodical. See our Carnival of Mathematics page for more information.

#tmwyk: mathematical play and conversations with my kid

Collage of mathematical play

#tmwyk is a Twitter hashtag which stands for some approximation of “Talking math(s) with your/young kids”. It is used to share mathematical interactions with children. It is also the subject of my MathsJam talk this weekend.

For me, I tend to use #tmwyk to share playful interactions with my son, following his interests and the mathematics that we find in the world around him. I’m not trying to teach anything in particular, nor am I trying to limit his interests to what might come up at school.

“Algebra?” said Madam Frout … “But that’s far too difficult for seven-year-olds.”
“Yes but I didn’t tell them that, and so far they haven’t found out,” said Susan.

Thief of Time, Terry Pratchett.
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