The first week of class we did numbers- more specifically, we did prime numbers, prime factorization, lowest common multiple and greatest common factors (and roots). It was a lot like a review of what we did in grade 9.
One question I had a slightly hard time with was this one:
5. Twin primes are defined to be consecutive odd numbers that are both prime. List the seven other twin primes less than 80.
I counted until 23, which is a prime number, and assumed that it should be on the list paired with 29. However, after a long period of thinking and not seeing 23 in the answer, I realized that 25 was the next odd number but 25 is not a prime number so the next twin pair would be 29 and 31.