NZ Level 3
Order of operations
Lesson

## Why we have order

In life, the order in which we do things is important. For example, we put the key in the car, before we start the engine. The same goes for solving number problems with more than one operator. Operators are those things that tell us what we need to do with the numbers, including addition (+), subtraction (-),  multiplication (×) and division (÷).

### The order

There are a number of conventions (rules) which need to be followed in order to solve these problems correctly, as we have seen when we've explored the order of operations before. Sometimes our problem may be a written one, so we can work out what to solve first. But if it's a number problem, then it helps to remember that the order we solve things is:

• multiplication and division first, from left to right
• addition and subtraction next, from left to right

In this video, we look at how real-life problems help to demonstrate why we need to follow the order of operations. If we don't, we end up with too many buses of students on our camp!

#### Worked Examples

##### question 1

Evaluate $6-15\div5$615÷​5

##### Question 2

Evaluate $12\times\left(5+6\right)-35$12×(5+6)35

##### Question 3

Evaluate $49-\left(37+\left(15\div3\right)\right)$49(37+(15÷​3))

### Outcomes

#### NA3-1

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