Englishfor English speakers
a
Determinative
—
A is used when the following word could be any of a certain type.
Compare "A book I saw on the shelf" and "The book I gave you yesterday".
a
Noun
—
A is the first letter of the alphabet.
The letter "a" comes before "b".
—
In some schools, an A is a very high grade.
Ron got an A on his earth science test.
hundred
Determiner
—
(ordinal hundredth) The number 100.
There are a hundred centimeters in a meter.
hundred
Noun
—
The number 100.
Ten tens is a hundred.
rouble
—
noun
(= ruble)
the basic unit of money in Russia