# June, 2020

## On Common Factors and Multiples

The marvellous @solvemymaths tweeted some time ago about finding least common multiples and highest common factors: I know the Venn diagram method for finding the Lowest Common Multiple is supposed to make it easier, but in my brain it just makes you do more maths. Also circumvents understanding if you're

## Wrong, but Useful: Episode 80/80

In this, the final episode of WBU, @reflectivemaths and I discuss: @samuel_hansen's antiracism post((get well soon, Samuel)). Dave and I both assert that Black Lives Matter and acknowledge that we have a significant amount of work to do to create a just society. In a whiplash-inducing change of tone, tooth

## Ask Uncle Colin: A Fraction of a Square

Dear Uncle Colin, I have been presented with this diagram: the marked points are a third of the way along the sides. I need to know what fraction of the grey square is shaded blue. Any ideas? Somehow Hued Area Defies Evaluation Hi, SHADE, and thanks for your message! There

## A Sudoku Surprise

Once upon a time, I was a sudoku fiend. They provided an outlet, a distraction, a hiding place – I could bury my head in one for, say, half an hour and whatever had been troubling me before was somehow less of an issue. It’s not an effective strategy for

## Ask Uncle Colin: An Octahedral Angle

Dear Uncle Colin, I have an octahedron, and I’m not afraid to use it! But I am afraid to find the angle between two adjacent faces. How would you do that? Protractors Lack Accuracy Tackling Octahedron Hi, PLATO, and thanks for your message! An octahedron is a shape made from

## Resolving an Unfinished League

Last week, the English Football League season was cancelled, with standings decided on a points-per-game basis in League One and League Two1 In League One, that led to Wycombe Wanderers leaping into the playoffs at the expense of Peterborough, who had accrued the same number of points but played a

## There is no Ask Uncle Colin today #strike4blacklives

In support of #strike4blacklives, there is no Ask Uncle Colin today. Please see Shut Down STEM to learn more. I will be spending the time I would have spend working reading Superior by Angela Saini in an attempt to fill some of the gaps in my knowledge. Black lives matter.

## Cav, Catriona and some hexagons

It’s always fun to tackle a puzzle from one of Cav’s posts - in this case, a Catriona Shearer puzzle; it looks like my solutions are completely unrelated to his, although in reality I tend to sneak the odd peek and take some inspiration1 I also liked that Cav shared

## Ask Uncle Colin: Two Numbers Close To 1

Dear Uncle Colin, How do I tell which is larger, $2^{-10^{-20}}$ or $1 - 2^{-10^{20}}$? - Unexpectedly Narrow Interval… Thank You! Hi, UNITY, and thanks for your message! As you’ve doubtless realised, both of those are “pretty much 1”. The question is, which is closer? As usual, there are several

## The Dictionary of Mathematical Eponymy: Randolph diagrams

A second-in-a-row Dictionary of Mathematical Eponymy post about Boolean logic today – and another example of a Very Neat Diagram. What is a Randolph diagram? You’ve seen - at least, I hope you’ve seen - Venn diagrams. Beastly things. I would chuck them out the window if I could, they