"He has good understanding" OR "he has a good understanding"

[CadleCrap]

Just that really. I am writing school reports and having a bit of a mind blank.

So should it be
James has a good understanding of ...

or James has good understanding of...

Or

does it not matter?

TIA

either

no actually why not jsut say " James understands maths well"

Good understanding in general
A good understanding of something specific.

"He has good understanding" can only be used generally. I wouldn't use this one as it's non-specific and not very informative.

"He has a good understanding of place value" is informative, specific and grammatically correct.

Cross-posted with Funky.

Bradsplit I am considering using "knowledge" instead of understanding!

Funky So it would be

He has good understanding of maths

but

He has a good understanding of trigonometry.

Thank you all.

I love pedants' corner

He has a good understanding of Maths.
He has a good understanding of trigonometry.
He has good understanding.