What is the 9th multiple of 2?

[Erebus]

or the 3rd multiple of 2?

Do they mean 9 x 2 (= 18!) and
3 x 2 (= 6 of course)

OR does the first mean 2x2x2x2x2x2x2 etc 9 times and the other
2x2x2? etc.

First, instinctive thought was 18.

Of course 'multiple' isn't newfangled (I know my HCFs from my LCMs) but 'the nth multiple of m' seems to be a usage we've not all come across - ergo, newfangled. And - while I'd have said 2x9 - evidently a possible source of parental confusion.

Multiple yes normal terminology "Xth multiple of Y" is definitely new to me. Oh well, fortunately DC never need help with their maths homework anyway, whatever the teachers are doing is obviously working for them.

No, jellybelly- when your DC move up school and get this sort of thing- you sidle over to the computer and ask Mumsnet. Works for me!

Again I agree with spanieleyes ... surely the concept of LCM (lowest common multiple) and HCF (highest common factor)

Both of which are used right through the maths curriculum can not be considered "superfluous" or "made up"