Question 19
From the list of 90 integers 21, 22, 23, …, 109, 110, only distinct even numbers are selected. What is the least number that must be selected to guarantee that two selected numbers have sum 100?
Answer format: enter the integer answer without units. Leading zeros are optional; the original paper uses four-digit boxes.
Answer format: enter the integer answer without units. Leading zeros are optional; the original paper uses four-digit boxes.