Discussion
The number of integers greater than 7000 using 2,4,6,7,8 without repetition, is
Answer: A
There are 168 such integers.
Using each of 2, 4, 6, 7, 8 at most once, an integer greater than 7000 is either a four-digit number starting with 7 or 8, or any five-digit number:
\[ \begin{aligned} \text{4-digit} &: 2 \times 4 \times 3 \times 2 = 48 \\ \text{5-digit} &: 5! = 120 \\ \text{total} &= 168 \end{aligned} \]
Counting only one of the two groups, or allowing repetition, gives the other options.
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