Given 9 natural numbers 1,2,3,4 .... 8,9. How many numbers must be put out to make sure there exist two numbers with a total of 10?
1 Answer
Aug 14, 2018
Six
Explanation:
If I understand the question correctly, we want to know the minimum size for a subset
Note that
On the other hand, note that we can partition
{1, 9} ,{2, 8} ,{3, 7} ,{4, 6} ,{5}
Then if