(1) A decimal, starting from a certain position in the decimal part, or appearing successively, is called a decimal.

(2) In 3.82, 5.6, 0.35, 0.002, 2.75, 3.2727 ... are finite decimal numbers, but () are cyclic decimal numbers ().

(3) 8.375375 ... can write.

2. Write the approximate values of the following cyclic decimals (keep three decimal places).

0.3333……≈ 13.67373……≈

8.534534……≈ 4.888……≈

3. Judgment (put "√" in the brackets for the right and "×" for the wrong)

(1) 1.4545 ... one decimal place is reserved) ≈ 1.4 ()

(2) The cycle segment of 2.453453 … is 435. ( )

(3) Circular decimals are infinite decimals. ( )

(4) The last digit of the decimal part of1.2323 … is 3. ( )

4. Calculate the following problems and express the quotient with cyclic decimals.

13÷ 1 1= 57÷32= 1 1.625÷9.3= 30. 1÷33=

Intelligent upgrade:

1. Can you compare the sizes of these decimals? Give it a try! (I can't get the circulation point when I send it. )

0.66○0.6 8.25○8.25 5.4 1○5.4 1

3.888○3.08 7.28○7.28 0.99○0.9999

2. Use simple symbols to represent the following cyclic decimals.

3.2525…… 17.065 165 1…… 1.066…… 0.333……

3. multiple choice questions. (Fill in the serial number of the correct answer in brackets)

The loop segment of (1) 2.235235 ... is ().

①2.235 ②2.35 ③235 ④235

(2) Among the following figures, the largest is ()

①3.8 1 ②3.8 1 ③3.8 1 ④3.8

(3) Numbers require three decimal places, and should be calculated to () decimal places.

① Two, two, three, four, four, five.

4. Application questions

Students from three classes in Grade Five took part in tree planting activities, and planted 220 trees. Class one planted twice as many trees as Class two, and Class two planted 20 more trees than Class three. How many trees are planted in each class?

Intelligence:

The sum of the two numbers is 1 1.63. Xiao Qiang moved the decimal point of an addend to the left due to carelessness in calculation, and the sum was 5.87. What are the first two addends?