On Friday, after lessons, a pupil came to find me. I don’t teach him this year, but have done so previously and I know him to be particularly interested in the subject and we often chat about what he’s currently studying in maths.
He sought me out for some help with a problem he had encountered: write 0.2 recurring as a decimal.
So we grabbed a scrap of paper and pencil and ‘did the math’ as they say in America:
Let x = 0.2222 … recurring
Multiply x by 10 to give:
10x = 2.222…
Now subtract x from 10x:
10x = 2.222 …
– x = 0.222 …
9x = 2
So 9x = 2, therefore
x = 2⁄9
I’ve always found this a neat little piece of maths, and my student did too.
And that’s two reasons why we teach:
- We get to use maths on a daily basis, and still get a buzz out of its simple brilliance.
- Sharing that knowledge with young people and helping them make sense of the world around them.
A great way to end the teaching week!