Integers:

**One/a boy**

Two boys

Three boys

Two boys

Three boys

Fractions:

**Half a cake/one half cake**

One and a half cake(s)

Three quarters of a cake

One and a half cake(s)

Three quarters of a cake

Zero:

**Zero boys**

No boys

Not a single boy

Absence of boys

No boys

Not a single boy

Absence of boys

More or less:

**More than one boy(s)**

Less than two boys

Less than two boys

These last ones come down to whether you think of "more" or "less" as part of the determiner or with scope over the whole NP.

(More than one) boys

or

More than (one boy)