A set of letters is normally called an alphabet.
an alphabet is a set of letters. All alphabets are composed of letters.
Set your computer on CD or DVD.
What relationship did the writers have
I work at a Kindergarten school...and we call them....guess what? lower case letters!!!
Consonants
Cuneiform?
set
That is called a font.
In formal language theory, a string is defined as a finite sequence of members of an underlying base set; this set is called the alphabet of a string or collection of strings. The members of the set are called symbols, and are typically thought of as representing letters, characters, or digits.
A null set. Although they could be sets of letters, sets of people, sets of animals, in fact sets of anything other than numbers.
an alphabet is a set of letters. All alphabets are composed of letters.
It's called fan mail fan letters
Why were the letters written? -
It depends on the number of letters in the set - which is not specified. If there are n different letters in the set, the answer is n*(n-1)*(n-2)*(n-3)*(n-4)
dawn
dialogue
In a set, as it is usually defined, elements can't be repeated. "Mathematics" has 8 distinct letters, so your set would have 8 letters. The number of possible subsets (this includes the empty set, and the set itself) is two to the power 8.