Page 16 - 新思维数学学生用书5 样章

1.2 Rounding decimal numbers

Exercise 1.2

1 Identify the numbers marked by arrows. Round each number to the nearest whole

number.
A B C

2 3 4 5 6 7 8 9

2 Round these numbers to the nearest whole number.

a 65.8 b 101.1

c 44.4 d 55.5

3 Round these measurements to the nearest whole centimetre.

a 2.8 cm b 8.5 cm

Round these measurements to the nearest whole metre.

c 7.3m d 0.3m

4 A number with 1 decimal place is rounded to the nearest whole number.
a What is the smallest number that rounds to 5?

b What is the largest number that rounds to 5?
Ask your partner to check your answers. Did you both choose the same numbers?

5

74.5 is 74 to

the nearest whole

number.

Is Marcus correct?

Explain your answer.

6 Use a calculator to help you answer this question.

Two numbers each with 1 decimal place round to 231 to the nearest whole number.

The sum of the two numbers is 462.
What could the numbers be?

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