Question

. How many strings are there of lowercase letters of length four or less, not counting the empty string

Answer 1

Answer:  475,254

This is one single number and not two separate numbers.

Delete the comma if your teacher requires it.

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Explanation:

I'm assuming letters can repeat.

There are 26 letters in the English alphabet.

There are,

• A = 26^4 = 456,976 strings of length four
• B = 26^3 = 17,576 strings of length three
• C = 26^2 = 676 strings of length two
• D = 26 strings of length one

Overall, there are A+B+C+D = 456,976+17,576+676+26 = 475,254 strings of length four or less.