Page 33 - Mathematics Coursebook

3.1 Understanding decimals

3.1 Understanding decimals

A decimal number always has a decimal point.
Example: 12.56 is a decimal number.
It has two decimal places because there are two numbers a$ er the decimal point.
You can write the number 12.56 in a place-value table, like this. ! e position of a digit in the table
shows its value.

Hundreds Tens Units • Tenths Hundredths Thousandths

1 2 s 5 6

!e digit 1 represents 1 ten and the digit 2 represents 2 units. Together they make 12, which is the
whole-number part of the decimal number.

!e digit 5 represents 5 tenths and the digit 6 represents 6 hundredths. Together they make
56 hundredths, which is the fractional part of the decimal number.

Worked example 3.1
The diagram shows a parcel that weighs 3.465 kg.

Write down the value of each of the digits in the number. 3.465 kg

The digit 3 has the value 3 units.
The digit 4 has the value 4 tenths.
The digit 6 has the value 6 hundredths.
The digit 5 has the value 5 thousandths.

) Exercise 3.1

1 Here are some decimal numbers.
32.55 2.156 323.5 4.777 9.85 0.9 87.669 140.01

Write down all the numbers that have a one decimal place b three decimal places.

2 Write down the value of the red digit in
each of these numbers. In part f, to work out the value of the 8, extend the
a 42.673 b 136.92 c 0.991 place-value table one more column to the right.
d 32.07 e 9.998 f 2.4448
3
‘The number 8.953 is bigger than 8 but smaller than 9’.

Is Xavier correct? Explain your answer.
Is Xavier correct? Explain your answer.
4 Sham has a parcel that weighs 4 kilograms and 5 hundredths of a kilogram.
Write the weight of Sham’s parcel as a decimal number.

32 3 Place value, ordering and rounding