Translation:Un deg pump
Welsh seems to do this more than any of the other languages I am studying. Very annoying.
I heard it's because these words weren't initially meant to be in the course but people reported it and they had to be added in as acceptable answers, not sure how true this is but it seems to fit.
Acceptable answers is one thing. I am fine with having loads of variation there - the Spanish course is very Latin American for instance but accepts pretty much any variations used in Spain even if never taught, but actually asking something untaught as a question is different. I have only seen this issue on the Welsh course, so I don't think it has to be an issue just to accept variations.
That depends. I'm not a fluent speaker so I'm not 100% sure, but some materials I've read say that the vigesimal system tends to be used with money and must be used with the time.
As far as I understand the older vigesimal system tends to be used up to 50 and the decimal system after 50, with older people preferring the vigesimal system and younger people preferring decimal.
E.g. Pum munud ar hugain wedi tri not dauddeg pump muned wedi tri for "twenty five past three".
In Welsh the vigesimal 25 is pump ar hugain, literally "five on twenty". When you are counting objects then the object comes between the pump and ar hugain, so the Welsh for "dog" is ci:
Pum ci ar hugain "Five dogs on twenty".
The decimal 25 is dauddeg pump, literally "two-ten five". This time when counting objects the object comes after the number:
Dauddeg pump ci "Twenty five dogs".
When counting like this Welsh uses the singular noun (here it's ci). The other way is to say "twenty five of something":
dauddeg pump o cwn, literally "twenty five of dogs" but in this way the grammatical plural is used.
Our policy on numerals is that we accept them in sentences where the translation is from Welsh to English because that shows the user can understand the Welsh word, which is the point of the course.
We don't accept numerals as answers for English to Welsh questions because this course is designed for English speakers and therefore there is no point in testing that someone understands numbers in English. The point of the English to Welsh questions is to learn the number in Welsh.
Besides the Welsh modern number system is one of the easiest to learn.