Page 14 - 新思维数学学生用书5 样章

1.2 Rounding decimal numbers

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

Think like a mathematician

Zara is thinking of a decimal number less than 1.

The hundredths digit is
four more than the tenths digit.
The sum of the tenths digit and the
hundredths digit is 10.

What number is Zara thinking of?
Make up a similar question to test your partner.

You will show you are specialising when you identify examples

that fit the given criteria.

Look what I can do!

I can explain the value of a digit in a decimal number (tenths and hundredths).

I can multiply and divide whole numbers by 1000.

I can multiply and divide decimals by 10 and 100.

1.2 Rounding decimal numbers

We are going to …

• round numbers with 1 decimal place to the nearest whole number.

Rounding makes it easier to describe and understand nearest round
numbers. It is easier to understand ‘an African elephant

is approximately 3 metres tall’ than ‘the average height round to the nearest ...

of an African elephant is 3.3 metres’.

13