"I want seven oranges."

Translation: Dw i eisiau saith oren.

[ElizaSnow1]

Why is it oren instead of orennau for this sentence?

[rmcode]

In Welsh numbers use the singular form of the noun.

[ElizaSnow1]

I never would have guessed that, thanks!

[Fenella_23]

It mentions rules like this in the tips/course notes. If you go to the website version of duolingo instead of the app you can find tips for each section of the course

[CymruBoy0]

If I click the tip for Oranges it even shows Orenau as an option. Is it wrong here just because there's a number involved instead of 'some oranges'?

[ibisc]

The pop-up hints are not context-sensitive. In some patterns the plural form would be used, but after numbers the singular noun is used.

[ElaineBeyn]

Why is oranges - Oren. I understood the plural is orenau which I put. Please explain.

[ibisc]

See rmcode's earlier answer to the same point.