Possible typo
Here is our last set of flashcards to provide you with the key takeaways from the section “Project-based Learning.”
Should be
Here is our last set of flashcards to provide you with the key takeaways from the section “put your learning into practice.”
Well, you check if it’s a multiple of every prime below sqrt(11009) ~= 105.
Though if you suspect he’s intentionally chosen a tricky number, a product of two large primes, you can look at the square numbers larger than 11009. In this case 11025 = 105^2, and 11025-11009 = 16 = 4^2, so 11009 = 105^2 − 4^2 = (105+4)(105-4) = 109×101