You may have already looked at how to write rules to describe decimal patterns. Now we're going to build on those skills and look at how to write a general rule using pronumerals. A pronumeral is a letter that is used to represent an unknown value in a mathematical expression or formula.

Watch this video now to learn more about using pronumerals to describe decimal patterns.

Worked examples

Question 1

Complete the pattern by adding $0.1$0.1 each time.

$0.1$0.1 $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$
If $c$c belongs to the same pattern, what is the next number?

Question 2

Complete the pattern by subtracting $0.3$0.3 each time.

$5.4$5.4 $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$
If $c$c belongs to the same pattern, what is the next number?

Question 3

Consider the following pattern.

What is the pattern?

$6.2$6.2 $12.2$12.2 $18.2$18.2 $\editable{}$ $\editable{}$ $\editable{}$

The numbers are increasing by $6$6.
A
The numbers are increasing by $60$60.
B
The numbers are increasing by $0.6$0.6.
C
The numbers are increasing by $0.06$0.06.
D
Now complete the pattern.

$6.2$6.2 $12.2$12.2 $18.2$18.2 $\editable{}$ $\editable{}$ $\editable{}$
If $x$x belongs to the same pattern, what is the next number?

Outcomes

NA3-1

Use a range of additive and simple multiplicative strategies with whole numbers, fractions, decimals, and percentages.

NA3-8

Connect members of sequential patterns with their ordinal position and use tables, graphs, and diagrams to find relationships between successive elements of number and spatial patterns.

Generalising patterns with decimals in tenths