Question

What is the minimum number of integers that you must pick between 0 and 9 (inclusive), such that two of them add up to 9?

Answer 1

6

Step-by-step explanation:

there are 5 different possible combinations of two integers that equal 9 when you add them together:

1. (0,9)
2. (1,8)
3. (2,7)
4. (3,6)
5. (4,5)

The worst case scenario is that you choose 0, 1, 2, 3, and 4, and adding any pair will not result in 9. So you will need to choose a sixth number and whichever that number is (either 5, 6, 7, 8 or 9), you will be able to add it to another one to get 9.

The best case scenario is that you choose only two and you are lucky enough to get a combination that works.