The number of different three-letter initials with none of the letters repeated that people can have is 17,576. This is calculated by taking the total number of letters in the alphabet (26) and subtracting the number of letters that would be repeated if initials were allowed to have repeated letters (10). The formula for this is 26^3 – 10^3 = 17,576.
Three-letter initials are often used to identify people or organizations. For example, the initials “FBI” stand for the Federal Bureau of Investigation, and the initials “USA” stand for the United States of America. Three-letter initials can also be used as a way to personalize items, such as monogrammed luggage or jewelry.
