Adjective/adverb + enough

Enough is an adverb. It normally comes after the adjective or adverb it modifies.

She is old enough to be a grandmother. (NOT She is enough old to be a grandmother.)
It isn’t big enough. (NOT It isn’t enough big.)
You were not running fast enough.
I can’t wear your shoes – I haven’t got big enough feet.

Enough + noun

Enough can be used before a noun phrase as a determiner. Note that before a noun with a determiner (articles, possessives or demonstratives), we use enough of.

We have got enough rice.
I couldn’t answer enough of the questions.

Position with adjective + noun

We have seen that enough comes after the adjective it modifies. But when enough modifies an adjective and noun together, it comes before the adjective.

Compare:

We haven’t got big enough nails. (We need bigger nails.)
We haven’t got enough big nails. (We need more big nails.)

Enough + infinitive

Enough can be followed by an infinitive.

She is old enough to know better.
These mangoes are ripe enough to eat.
I haven’t got enough money to buy an apartment.