Draw a picture first and calculate.

The length of the rectangle is 4 meters.

Second, solve the problem.

1.

(0.24+0.06)× 12+0.4

=0.3× 12+0.4

=3.6+0.4

=4 km

The canal is 4 kilometers long.

2.

(90+8)÷2

=98÷2

=49 (tree)

Answer: Class Two students planted 49 trees.

Third, choose to fill in the serial number in brackets.

1.②

2.②

3.②

4.③

5.②

Page 7

1. Look at the pictures and fill in the blanks.

90

contrary/opposite

②

Shun 90

Second, according to the product of 1 column, quickly write the product of two numbers in each column.

4800 4800 48 4.8 48 4.8 4.8

Third, fill in the numbers according to the law.

17

8 1

Fourth, use simple methods to calculate the questions.

4.8×22-4.8× 12

=4.8×(22- 12)

=4.8× 10

=48

14. 15+2.9+ 1.85

= 14. 15+ 1.85+2.9

= 16+2.9

= 18.9

13.75-(3.75+6.48)

= 13.75-3.75-6.48

= 10-6.48

=3.52

5. Fill in the blanks.

The area of a triangle is (a? ), the area of the square is (4a? ), the area of the trapezoid is (5a? )。