In KS2 Maths children will come to understand decimal numbers. In Year Six children should know the place value of figures in decimal numbers to three places - tenths, hundredths and thousandths - and also be capable of adding and subtracting with decimals. They should also be confident when rounding decimal numbers up or down, and be familiar with sums involving decimal measurements such as metres/cm or £/pence.

Decimal numbers contain decimal points, on the left of which are units and on the right tenths, hundredths and thousandths. We use decimal numbers as an alternative to fractions to describe numbers that are smaller than a unit. For example, the fraction ^{1}⁄_{8} could also be written as 0.125. Here we have 1 tenth, 2 hundredths and 5 thousandths. Decimal numbers make addition, subtraction, multiplication and division of fractions much easier. For this reason we have decimal measurements like metres and kilos which all use tenths, hundredths and thousandths.

Take this quiz and find out how well you know decimal numbers.

1.

What is 1.23m + 63cm?

1.86m

74.23m

7.53m

186m

Convert the cm into metres and you will have 1.23 + 0.63 giving 1.86m

2.

What is the next number in the sequence 0.007, 0.008, 0.009?

0.001

0.1

0.01

1

The numbers are going up by 0.001, or ^{1}⁄_{1,000} every time

3.

What does the digit 1 represent in 0.251?

1 tenth

1 thousandth

1 unit

1 hundredth

Remember - tenths, hundredths, thousandths

4.

Which is the decimal fraction equivalent to nine and two thousandths?

9.002

9.2

9.02

0.092

Units are on the left of the decimal point

5.

What is the figure 8 worth in 2.089?

8 units

8 hundredths

8 tenths

8 thousandths

2.089 is 2 units, 0 tenths, 8 hundredths and 9 thousandths

6.

Which is the largest of these numbers?

0.3

0.003

0.033

0.03

7.

How is 0.023 changed to 0.23?

Multiply by 10

Divide by 100

Divide by 10

Multiply by 100

When we multiply by 10 the digits move one place to the left

8.

Which is the smallest of these numbers?

0.001

0.1

0.01

0.011

9.

Which is a decimal fraction halfway between 6.52 and 6.53?

6.55

6.521

6.525

6.531

There are 10 thousands in a hundredth so half of a hundredth is 5 thousandths

10.

How is 0.7 changed to 0.007?

Multiply by 10

Divide by 100

Divide by 10

Multiply by 100

When we divide by 100 we move the digits two places to the right