Demasiado (agreeing in number and gender) vs demasiado (not agreeing with number and gender)

Question

I’ve been getting the quantifiers mixed up with how to remember they do agree with the gender and plural when it’s applied.

Especially for demasiado and poco. When is it that it does match the thing it’s describing; and when does it not?

Kind regards,

Fran

Accepted Answer

Hola Fran,
Demasiado and poco agree in gender and number if they are adjectives. So if you see them accompanying a noun, they will be adjectives:

Tengo demasiadas monedas. (I have too many coins.)
Tengo pocas monedas. (I have [very] few coins.)

But if demasiado or poco don't accompany a noun, they will be modifying the verb, therefore they will be adverbs (not adjectives). In this case they stay the same:

He comido demasiado. (I ate too much.)
He comido poco. (I ate [very] little)

I hope this helped.
You can see here the lesson for when they are adverbs. Have a look. 
Saludos,
Inma