Look at this stupid maths question on Kidblog

[catinb00tz]

How ridiculous is that? Or am I being stupid?

Have spent far to long trying to figure out why you thought it was wrong.

the dot means recurring so it' fine - I wouldnt expect primary age kids to know that? or would y5/6?

I could work it out, but I wouldn’t expect many children to be able to do it- depends what age it’s aimed at.

Tbf, as a person who writes mathematical software I wouldn’t accept 0.6 with a dot in any technical document for exactly this reason! 2/3 is much easier to read and leads to less confusion.

Though, I understand that it’s useful for people to know what the dot means.

DS (yr 6) claims to have never been taught about the dot

Maths was my best subject in school, did very well in it - and we didn't learn that at all, so I suspect it is something that became more common in more recent years (showing my age here!)

well, I teach year 5 and 11+ tuition which is based on up to year 6 curriculum, and I have never seen the dot before.

I remember my DD showing me that 0.9 recurring = 1. Still blows my mind.

@ShetlandWife

Maths was my best subject in school, did very well in it - and we didn't learn that at all, so I suspect it is something that became more common in more recent years (showing my age here!)

Depends upon your age. We did it in [cast memory back a geological time era or two] 1983.

I do seem to remember that the dot should be on the second decimal place though - from O level maths - so 0.66 dot on the last one - but I may be mis-remembering

@WorkingItOutAsIGo how does 0.9 recurring = 1 ?

Just asked my daughter, she says she thinks she was taught it in Year 4 or 5.

I've just asked DC currently in Y5 - claims to have never heard of it. DC in Y8 knew it meant recurring - says has known about it since about Y4, same school. Says it all about lockdown learning ....

@catinb00tz

Try and tell me what the difference between 1 and 0.99 recurring is? As in - give me a number......

I definitely know what the dot means. I’m surprised people don’t know. I learnt in primary school - and that’s a long time ago.

0.1 recurring? :)

I know you're right, it goes on forever getting closer to 1, it's just hard to accept

Since when was it a dot? When I was at school we had to write a tiny little r next to the number for recurring. And I'm under 30

Since when was it a dot? When I was at school we had to write a tiny little r next to the number for recurring. And I'm under 30

Are you sure you aren’t getting confused with an r for remainder?

[quote catinb00tz]@WorkingItOutAsIGo how does 0.9 recurring = 1 ? [/quote]
Because you round up when the last digit is 5 or greater, round down if it's 4 or less.

So 1.426789 rounded
to the nearest whole number would be 1,
to 3 decimal place would be 1.427
to 1 decimal place would be 1.4

to 7 decimal places would be 1.4267890

r is remainer. Dot is recurring - but back in the day I think it was a dash above the number not a dot?

The 0.9 recurring thing = 1 bothers me too, even though I know it's provable! I just don't like it.

You can prove it the same way GCSE students are taught to convert any recurring decimal to a fraction.

Call 0.9 recurring x.

Then if you multiply both sides by 10, you get 9.9recurring = 10x. If you subtract the initial equation from each side, you get 9 = 9x (because the recurring 9s all cancel out when you subtract). The to find x, you just divide both sides by 9. so x = 9/9 = 1.

I still don't like it.
It shouldn't be true. It just is.

But the recurring dot has certainly been taught by some primary schools in Year 5 or 6

(it's not just rounding it up to 1, as that's not the same as saying that it IS 1, it's just saying that if you round it, the closest number is 1).

(And we also use to use a dash to show recurring, but of more than one number. We'd put a dot on a single recurring number, but a line across more than one recurring. now they seem to put a dot on each, if there's two, or a dot on the start and end if there are more than two).

(And it gets taught when they do long division and start going into decimal answers)

Easier for 0.9 recurring = 1

1/3 = 0.3 recurring

Multiply both sides by 3.

1 = 0.9 recurring

@Thimbleberries that hurt my brain

I'm in my 50s. A dot has meant recurring all my mathematical life.

That said, I don't think knowing this is on the GCSE syllabus...