A combination of letters and numbers and symbols is a character set. To use a formula to combine letter and numbers and symbols is known as concatenation.
Algebra
There is no specific number of symbols that can be used. You can use any letter of any alphabet.
It makes clear that the following symbols should be read as numbers. Some Braille symbols do double duty as letters and numbers, and there are symbols that flag that the following should be read as numbers or as letters. en.m.wikipedia.org/wiki/English_Braille#Contractions
They are called symbols.
Individual letters, numbers or special symbols such as @#$%^& found on a computer keyboard.
i do not know * * * * * The Greek letter, capital sigma, Σ.
It is just the alphabet, but symbols for each letter. Go to ArtemisFowl.com, click games, then click decoder. It shows all the letters with their symbols above them. The symbols are the same for every book.
it is called a variable not a letter
A variable.
A letter used to represent numbers is called a variable; the most common ones are 'x' and 'y'.
coefficent