This was a relatively simple puzzle, and I got correct answers from Suman Saraf, Mohit Khare, Vishal Poddar and Pratik Poddar – thank you all!
The answer is 1024.
An easy way to think about this is to create a 10 digit binary number, where each digit represents one of the friends each. 0 means the friend is not coming, and 1 means that the friend is coming. Note that there can be 2^10 combinations here, and each of them represents a distinct combination of friends coming.
Hope you all enjoyed the puzzle!
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