5. (5 points) From the ten digits $0 \sim 9$, the pair of different numbers with the largest product is $\qquad$ multiplied, the pair with the smallest sum is $\qquad$ and $\qquad$ added, and the pairs that add up to 10 are $\qquad$ pairs.
【Answer】Solution:
The largest product is $9 \times 8$
The smallest sum is $0+1$
Pairs that add up to 10 are $1+9,2+8,3+7,4+6$ so the answers are $9, 8, 0, 1, 4$