Question

What will be the best approach to finding all the prime numbers less than 75 that leave an odd reminder when we divide them with 5?

Answer 1

Numbers that leave an odd reminder when we divide them with 5 means, they will be in the form of
(5x+1) or (5x+3)
This will be the best way to start with, and then you can add constraints like the number should be less than 75 or the number should be prime.

Answer 2

Except 2 and 3, all the prime numbers are in a form of (6k +1) or (6k -1)
Therefore, you can use the formula to write down the prime numbers as:
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 61, 67, 71, 73

Now, you can separate numbers as per the requirement that are:
3, 11, 13, 23, 31, 41, 43, 53, 61, 71 and 73