Question 2: 36 red pens

Let the number of participants in the third question 389 be x and the number must be an integer (there is no half of them-), so 0.

The fourth problem is to reduce the price by 0.06 yuan.

Question 5: 9 out of 8

Question 6: 1280

PS: the sixth grade of primary school is a bit difficult-

Dare to give more points! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !