This is for MC I-A, right?

Note 2.26 (and similarly 2.27) are really just two questions asked together. For 2.26 the problem wants you to find the prime factorization of 325 and then separately find the prime factorization of 391. Recall, for example, the prime factorization of 180 is 2^2 * 3^2 * 5.

For 2.28, here's a hint: Consider the number 9876543. The sums of the pairs of consecutive numbers are 9+8=17 (prime), 8+7=15 (not prime), 7+6=13 (prime), etc., until 4+3=7 (prime). The problem is asking to find the smallest number so that ALL of these sums are prime.

Hope this helps!

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