There is only one empty square remaining in column one so we can enter the 3 to complete that column. Having the 3 in this square of the cage allows us to deduce the other two numbers which will result in our target number. Since the target number is 8 and we already have the 3, the two remaining numbers must add up to five (8 - 3 = 5).
So we can deduce that the two remaining numbers are either 1 and 4 or 2 and 3 (Remember, a number may repeat within a cage as long as it does not repeat in any row or column.) Can you figure out how we know which combination to use?
Complete A Column
Logic Leads Us On Again