Decimal numbers are the basis of metric measurements. They make calculations so much easier when converting from centimetres to metres, or from kilograms to grams for example. That’s because larger metric units are divided into tens, hundreds or thousands of smaller ones.

This series of quizzes is a little more difficult than those before it. However, by now you should have a very good grasp of decimal numbers, so you’ll be more than capable of answering these questions. If you are in any doubt, then go back and revisit our easier 11+ maths quizzes to get more practice.

Most of the questions you’ll find here concentrate on converting one measurement into another – something you’ll be called on to do often in real life. So, the more you familiarise yourself with doing it, the better placed you’ll be.

Take your time and read the helpful comments after each question. But, most of all, enjoy!

1.

What was 9.87654 multiplied by if the answer is 987.654?

100

10

1,000

10,000

The rule for multiplying by a whole number beginning with 1 and followed by one or more zeros, e.g. multiplying by 10, 100, 1,000, ... is as follows: When multiplying by such a number, move the decimal point to the right by the same number of zeros as in the number: 100 × 9.87654 = 987.654: the decimal point has moved two places to the right = the number of zeros in one hundred

2.

A gold bar weighs 12,442.61 grams. How many kilograms does a gold bar weigh?

1.244261 kg

1,244.261 kg

124.4261 kg

12.44261 kg

There are 1,000 g in 1 kg, so in 12,442.61 g there are 12,442.61 ÷ 1,000 = 12.44261 kg

3.

How many kilograms are there in 7,531.09 grams?

0.753109 kg

7.53109 kg

75.3109 kg

753.109 kg

There are 1,000 g in 1 kg, so in 7,531.09 g there are 7,531.09 ÷ 1,000 = 7.53109 kg

4.

The marathon is a race over a distance of 42.195 kilometres. How many metres is that?

4,219,500 m

421,950 m

42,195 m

4,219.5 m

There are 1000 m in 1 km, so in 42.195 km there are 227.65 × 1,000 = 42,195 m

5.

What was 987.654 divided by if the answer is 0.987654?

1,000

100

10,000

10

The rule for dividing by a whole number beginning with 1 and followed by one or more zeros, e.g. dividing by 10, 100, 1,000, ... is as follows: When dividing by such a number, move the decimal point to the left by the same number of zeros as in the number: 987.654 ÷ 1,000 = 0.987654: the decimal point has moved three places to the left = the number of zeros in one thousand

6.

What is 14,253 centimetres in metres?

1,425.3 m

1.4253 m

14.253 m

142.53 m

There are 100 cm in 1 m, so in 14,253 cm there are 14,253 ÷ 100 = 142.53 m

7.

What does 0.00025 have to be multiplied by to give 2.5?

1,000

10,000

100,000

100

For 0.00025 to become 2.5, the decimal point will have to move 4 places to the right. You will have to multiply 0.00025 by 10,000 - which has 4 zeros

8.

How many square centimetres are there in 15.3 square metres?

1,530 cm²

15,300 cm²

153,000 cm²

1,530,000 cm²

Be careful of squares! There are 100 cm in 1 m, so in 1 sq m there are 100 × 100 = 10,000 sq cm. In 15.3 sq m there are 15.3 × 10,000 = 153,000 sq cm

9.

What is 21.63 kilometres in centimetres?

2,163 cm

21,630 cm

2,163,000 cm

216,300 cm

Convert km to m by multiplying by 1,000. So, 21.63 x 1,000 = 21,630

Next, convert m to cm by multiplying by 100. So, 21,630 x 100 = 2,163,000

Next, convert m to cm by multiplying by 100. So, 21,630 x 100 = 2,163,000

10.

How many kilograms are there in 2.3 tonnes?

2,300,000

23,000

230

2,300

There are 1,000 kg in 1 tonne, so in 2.3 tonnes there are 1,000 × 2.3 = 2,300 kg