 # Write multi-step number sentences from descriptions

Lesson

Learning mathematics is like learning a language. Even better, we can use maths to describe patterns or relationships between two things. Number sentences, called equations, are like stories telling us how a value has been changed to produce another value.

## Writing Equations

Just like some clever people can translate between two languages, we are now going to look at how to translate between English and Maths. Good news- you've already started learning how to do this (even if you didn't realise it)! Let's look at an example:

• In English: "I had $5$5 stickers. I earned another $3$3 stickers. Now I have $8$8 stickers."
• In Maths: $5+3=8$5+3=8

When we translate from Maths to English, we don't know as much of the "story" but we can still describe how the numbers change. Let's look at how a number (let's call it $N$N) has been changed.

• In Maths: $N+5=12$N+5=12
• In English: "When we add a number and $5$5 together, then answer is $12$12."
Did you see?

Notice how instead of $N$N, I wrote, "a number."

Don't forget!

Just like there's a proper way to write sentences in English, make sure you consider the order of operations when writing equations. Otherwise, like Yoda you will sound, and confusing it will be!

#### Worked Examples

##### QUESTion 1

Which number sentence means:

"The quotient of $6\times9$6×9 and $6$6 is subtracted from $200$200."

1. $6\div\left(6\times9\right)-200$6÷​(6×9)200

A

$6\times\left(6\times9\right)-200$6×(6×9)200

B

$200-6\times\left(6\times9\right)$2006×(6×9)

C

$200-\left(6\times9\right)\div6$200(6×9)÷​6

D

##### question 2

Use the rule to complete the table of values:

"The starting number is doubled, then $4$4 is subtracted."

1.  Starting Number ($N$N) $12$12 $13$13 $14$14 $15$15 Answer ($A$A) $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$
2. Which of these equations describes the rule above?

$A=2\times\left(N-4\right)$A=2×(N4)

A

$A=N\times2-4$A=N×24

B

$A=N^2-4$A=N24

C

$A=2+N-4$A=2+N4

D

##### QUESTION 3

Use the rule to complete the table of values:

"The starting number has $9$9 added to it. The sum is then multiplied by $5$5."

1.  Starting Number ($N$N) $4$4 $5$5 $6$6 $7$7 Answer ($A$A) $\editable{}$ $\editable{}$ $\editable{}$ $\editable{}$
2. Which of these equations describes the rule above?

$A=N+9\times5$A=N+9×5

A

$A=\left(N+9\right)\div5$A=(N+9)÷​5

B

$A=N+5$A=N+5

C

$A=\left(N+9\right)\times5$A=(N+9)×5

D