-9^2 = -81

What's wrong with 2>x>1? I can see a problem with 2 < x < 1, but your example looks legal to me, even if it might be more conventional to write it 1 < x < 2.

When you say it, it's difficult to hear the difference between
minus nine-squared
and
minus nine, squared

It's like me getting puzzled by a shampoo bottle saying "no buildup formula" wondering what "buildup formula" was and why they had removed it, when it's actually saying it has a formula to prevent buildup.

cant it‘s not down to calculator use, I don’t think, it’s simply lazy recording when even doing basic calculations like the aforementioned area of a triangle.

You are rather unusual in being maths trained and primary, I don’t know if your other primary colleagues would have a mathematician’s natural visceral reaction to seeing that sort of monstrosity?

I had a massive argument with my A-level class the other day about an inequality expressed as 2>x>1. Unacceptable.

Ds’ maths teacher answered 81 although his exact words were ‘what’s -9 squared or -9 x -9’

That's probably a key difference - in primary, calculators aren't used, so that sort of recording would imply a lack of understanding (of a key point that we teach throughout primary).

In secondary, the understanding may be there but the replication on paper of what is typed into a calculator results in this type of 'lazy' / inaccurate recording.

Almost certainly.

I wonder if it's because they're used to using calculators? They do 4x6 and press equals, then press /2, then equals - and this transfers to written maths.

It's not that they don't understand =, it's that they are rushing ahead to do the next bit and just consider the last thing they have written down. The = is history by that point as far as they're concerned.

4 x 6 = 24 / 2 = 12 cm^2 would I kick up a fuss?

I've always told DD2 not to do this, but she still does.
As she is now y10 I sometimes think I've bigger issues to worry about. The one I'm 'all over like a rash' is writing the blasted formulae down first, then putting in the numbers, then working it out!

4 x 6 = 24 / 2 = 12 cm^2 would I kick up a fuss? Top set, yes, bottom set I’d be bloody delighted they remembered to divide by 2.

Upper primary here - and I am all over that kind of thing like a rash, so it is interesting that a secondary teacher would let it lie under some circumstances.

A key objective, even in early primary maths, is the understanding of the equals sign as a balance - and this example would show that a child doesn't have that basic understanding, which we would see as a significant issue.

Oh no didn’t mean do it. I like the sound of that world though.

Too late, 1pm, lunchbreak over. Back to my spreadsheets...

Love it sounds great

Marsha - I could email around 100 actuarial colleagues if you wanted more answers , but I wouldn't want to kill my inbox or spend the day refereeing endless discussions...

Agree it is a good thread. I like the part when actuaries get asked.

Agreed, Stealth, as shown in my Excel screenshot above. Whatever way a cell is formatted to appear, the entry of numbers into formulae still uses a minus sign for negative numbers. (So you type -9 and it appears as (9.00) if you have an accounting format).

My screenshot above shows that for Excel -92 = 81, but 0-92 = -81.

My iPhone calculator has that separate +- just looked.

I just found my old calculator under a pile of rubble, it has a separate +|- button on it to differentiate between negative numbers and the subtraction operation. So much clearer for students back in the day.

"
Excel is different, it uses brackets to demonstrate negative numbers."
It might do that if you pick a specific format setting but it isn't a universal truth. I don't have it set that way, excel shows me negatives with a minus sign.

But if the exam board want the answer of 81

If an exam board wanted an answer of 81 the question would be asked in a different way to the OP. I can 100% guarantee if the question asked the way it was framed in the OP was answered as 81 by an examiner there would be an outcry. The answer to the OPs question as it is asked in her OP is -81.

But if the exam board want the answer of 81, then teachers are teaching the children to do basic maths, the EU can board are adding brackets to leave the children in no doubt of how to do the sum.
To confuse school age children at this state in their education will simply lead to them losing marks.

Excel is different, it uses brackets to demonstrate negative numbers.

DD asked her maths teacher
He said the answer wanted will be 81.
He marks exams for year 11.
If anything else is wanted brackets will be used

Link the teacher to this thread

Three actuaries said -81, one (my manager ) said +81. The trainee who has a Physics PhD offered explanations for both answers but went with -81.

By the way, I am aware that Excel doesn't help. It treats a unitary minus sign differently from an operational minus sign - see attached.

But the minus sign in a negative number is a subtraction symbol.