It is called a complex number.
a number written down in words
A rational number
The number 400 is written in words as four hundred.
Half a billion.
It is called a complex number.
a number written down in words
It is still a number.
A rational number
A rational number
The number 400 is written in words as four hundred.
Complex
A whole number.
They are called "compound words."
Half a billion.
Nineteen million.
ninety-nine