Page 17 - 新思维数学学生用书6 样章

1 The number system

Look back over your answers.
Did you use the worked example to guide you?
Did you find any question particularly hard? Why?

Think like a mathematician

The sides of a rectangular face on a cuboid
are measured in centimetres to 2 decimal

places using a micrometer (an instrument
for measuring length accurately).

The measurements are rounded to the nearest

whole number. They are 5 cm and 6 cm.
What is the smallest possible perimeter of

the rectangle?

What is the largest possible perimeter of the rectangle?
Investigate the smallest and largest perimeters for other rectangles

if the measurements have been rounded to the nearest centimetre.

You will show you are specialising when you work out solutions.
If you explain your results for a number of rectangles, you will show you

are convincing.

Tip

Think about the smallest number with 2 decimal places that

rounds to 5 cm, then think about the largest number with
2 decimal places that rounds to 5 cm. Do the same for 6 cm.

Look what I can do!

I can round a number with 2 decimal places to the nearest whole number.

I can round a number with 2 decimal places to the nearest tenth.

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