Unit 2 Section 2 : Decimals and Place Value

In this section we will look at the place values to the right of the decimal point.
In the example questions, work out the answer then click Click on this button below to see the correct answer to see whether you are correct.

Place values for decimals

The number 1.743 can be broken into four parts:

Example
What is the value of the '6' in the number 2.164?

Sorting Decimals

We can sort decimal numbers into order, just like we can sort whole numbers.
Imagine we want to sort these numbers: 0.5, 0.95, 0.905, 0.59, 0.6, 0.9

Comparing these numbers is easier if we write all the numbers with the same number of decimal places.
Now we have: 0.500, 0.950, 0.905, 0.590, 0.600, 0.900

The extra "0"s on the end make no difference to the value of the number, but they are easier to compare.
We can now see that sorting these numbers gives: 0.500, 0.590, 0.600, 0.900, 0.905, 0.950

After removing the extra "0"s, the final answer is: 0.5, 0.59, 0.6, 0.9, 0.905, 0.95

Example
Sort these numbers into order:
0.7, 0.27, 0.72, 0.702, 0.207, 0.2

Rounding to a certain number of decimal places

If we want to round 4.732 to 2 decimal places, it will either round to 4.73 or 4.74.
4.732 rounded to 2 decimal places would be 4.73 (because it is the nearest number to 2 decimal places).
4.737 rounded to 2 decimal places would be 4.74 (because it would be closer to 4.74).
4.735 is halfway between 4.73 and 4.74, so it is rounded up: 4.735 rounded to 2 decimal places is 4.74.

Examples
(a) What is 5.79 rounded to 1 decimal place.

(b) What is 3.242 rounded to 2 decimal places?

 

Exercises

Work out the answers to the questions below and fill in the boxes. Click on the Click this button to see if you are correct button to find out whether you have answered correctly. If you are right then will appear and you should move on to the next question. If appears then your answer is wrong. Click on to clear your original answer and have another go. If you can't work out the right answer then click on Click on this button to see the correct answer to see the answer.

Question 1
What is the value of the "5" in each of the numbers below? Give your answer as a decimal.

(a) 0.45

(b) 0.54

(c) 5.74

(d) 3.415

(e) 4.258

(f) 3.502

Question 2
Write the numbers below in order, smallest first. Separate your answers with commas, like this :

0.85, 0.9, 0.8, 0.58, 0.6, 0.5, 0.87

Question 3
Write each of the numbers below correct to one decimal place.

(a) 1.47

(b) 3.68

(c) 0.45

(d) 3.751

(e) 4.08

(f) 5.005

Question 4
Write each of the numbers below correct to two decimal places.

(a) 3.444

(b) 8.555

(c) 0.321

(d) 4.7612

(e) 0.3002

(f) 4.1050

Question 5
Write these numbers in descending order, largest first.

0.7, 0.2991, 1.05, 1.508, 0.58, 2.4

Question 6
You are given the digits 3, 4, 0, 7 and the decimal point.
Each digit must be used only once, and the decimal point must appear between two digits.

(a) What is the largest number you can make?

(b) What is the smallest number you can make?

You have now completed Unit 2 Section 2
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Produced by A.J.Reynolds January 2001