90 690 70 2000 5/9

4/5 2 10 1 2.2

Second, use vertical calculation.

372÷7=53…… 1 545÷5= 109

52×49=2548 80×45=3600

3. Fill in "+","-"×" and make the equation hold.

1."+""-""-""+"

2."×""+""÷""-"

Fourth, find the perimeter and area of the picture below.

Circumference: 9×4+8=44 cm

Area: 9×9-3×4=69 (square centimeter)

Fifth, solve the problem.

1. Solution: (80+75+68+70+92)÷5=77 (person)

A: On average, 77 people go to the library every day.

2. Solution: (1)48× = 16 (human)

A: There are 16 people.

(2)48×30 (person)

A: There are 30 people.