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Supermarket Maths

A while ago Colin Beveridge. (@icecolbeveridge), or possibly his friend the mathematical  ninja, wrote this piece which looked at ice cream containers and chastised them for the practice of measuring themselves in mass (ie grams) and giving portion sizes in capacity (ml), yet not giving a density or any other sort of help to convert between the two. Don’t worry (spoiler alert) Colin did, of course, find a fix, and although I thought the practice strange I thought little more about it.

Until today, that is, when I went into the supemarket to pick up a few bits and the first thing I picked up was this bottle if Encona Hot Sauce (Other sauces are available, but this is my favourite):


As you can see, the good people at Encona have quoted the mass and the capacity in their bottle! My second thought was “if only Colin’s Ice Cream company thought like this!” (my first had been, “I bet I can use this in a lesson”!)

As I wandered round the supermarket I couldn’t help but think “I don’t remember ever seeing that on Encona bottles before.” So when I got home I checked, and sure enough, just mass no capacity:


I wondered what prompted the change, then, while unpacking the shopping I noticed this:


Heinz are at it too! This is the back of their garlic sauce! Now my mind started to race, have the government passed legislation to enforce the labelling of packaging in both capacity and mass? If so, why? Did Colin, or one readers, start a petition? A campaign? Was there a March on Downing Street? Will the law be enforced by the maths police?

Who knows? But I certainly think there are some good lessons to be had from it. I also noticed this whilst unpacking:


6 bars, 147 grams, so 24.5 grams each? Is it just me, or does it seem a strange number? The weird e means “estimated” (or so I’m told), so why estimate to 1dp when an integer value would be so much simpler? Ah, the strange world of supermarket Maths. I also wonder whether STD is the best abbreviation to use when selling a product…

Categories: Maths
  1. December 11, 2013 at 8:17 pm

    There are very tight rules about the estimate ‘e’

    • December 11, 2013 at 8:49 pm

      Extremely interesting, and an article with a ton of possibilities for exploration in lessons! Thanks.

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