I picked this up on social media and used it with my class and for our department meeting! Try it! It just feels like a neat little summary of one of the key observations about public understanding of, in this case, numeracy, but I think it goes deeper than that. On one level I think this leads nicely in to a discussion about estimation techniques . Use it with students and teachers and listen to the different ways it gets done and you will learn a lot about the way people think. we could get in to the use of the word mathematically too. Then I think, and probably most relevant for our maths apps students is the ToK angle of how most of us are unlikely to have a useful intuitive response to this question. We are out of our decimal Milieu, and the numbers are just big enough to be outside the range that most of us regularly estimate with. Anyway, I just thought it was worth sharing so you could have some good conversations too. Have a great day!