1. Heping Primary School has 6 grades and 5 classes in each grade, with an average of 45 students in each class. How many students are there in the school?

45×5×6

=225×6

= 1350 (person)

A: The whole school 1350 students.

2. Xiaoming reads books. If he reads 19 pages every day, it will take 32 days. Now he reads 20 pages every day. Can he finish it in 30 days? How many pages are left?

19×32-20×30

=608-600

=8 pages

A: I can't finish reading it. There are eight pages left.

3. Xiaohua walks from home to school 15 minutes. She can walk 56 meters per minute and go back and forth once a day. How many meters does it need?

56× 15×2

=840×2

= 1680 (m)

Answer: About * * * walk1680m.