2. The number of positive integers less than 1000 that are not divisible by 5 and 7 is
A. 688
B. 686
C. 684
D. 658
2. B $999-\left[\frac{999}{5}\right]-\left[\frac{999}{7}\right]+\left[\frac{999}{5 \times 7}\right]=999-199-142+28=686$. Therefore, the answer is B. Note: The number of positive integers less than $n$ and divisible by $d$ is $\left[\frac{n-1}{d}\right]$.