7. The result of the calculation $123456789 \times 8$ is almost the same as 987654321 except that two of the digits are in a different order. What is the sum of these two digits?
A 3
B 7
C 9
D 15
E 17
7. A The units digit of $123456789 \times 8$ is 2 , since $9 \times 8=72$. So, if the statement in the question is correct then the two digits which are in a different order are 1 and 2, whose sum is 3 . As a check, $123456789 \times 8$ is indeed 987654312 .