 Hong Kong
Stage 2

# Generalising patterns with decimals in tenths

Lesson

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.

#### Worked examples

##### Question 1

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

1.  $0.1$0.1 $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$
2. 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.

1.  $5.4$5.4 $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$
2. If $c$c belongs to the same pattern, what is the next number?

##### Question 3

Consider the following pattern.

1. 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
2. Now complete the pattern.

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