I showed you zero to 15 in the decimal to Binary and 15 is 1111 in binary. Now, here are letters converted to binary in what is called an "Alpha Numeric" format. As you can see 8 binary places are needed for each upper case and lower case letters in the alphabet. for example a lower case "a" is represented as a = 01100001 in binary which is how computers keep it stored in memory.
So, when you see letters for example on an HTML web page in actual memory of a computer they each take 8 places to represent. So, stored in memory each letter takes 8 binary spaces.
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On Convert Binary dot com you can find the letters of the latin ASCII alphabet in their binary code ... Check out the binary numbers translation table too.
ALPHABET IN BINARY, CAPITAL LETTERS
ALPHABET IN BINARY, LOWER CASE