Question 15
There are eight numbers namely 1, 2, 3, 4, 5, 6, 7 and 8. Choose at least two different numbers from the eight numbers such that the difference of any two of the chosen numbers neither equals to 2 nor 6 (For example, if 1 is already chosen, 3 and/or 7 cannot be chosen). What is the number of different ways to choose the numbers?