 Hong Kong
Stage 1 - Stage 3

# Using a Calculator for Fractions

Lesson

We've already looked at how to use a calculator to solve calculations with whole numbers. Now we are going to build on that knowledge and look at how to use a calculator to solve calculations with fractions. Just like with whole numbers, it's important to consider whether the answer is reasonable. Although calculators are very smart, they just do what you tell them. They won't necessarily pick up on mistakes.

Firstly, let's get familiar with the fraction button on your calculator. There are a couple of examples of what they may look like below. It will just depend on the brand of your calculator so see if you can find a corresponding button on your calculator. If not, ask your teacher or a friend to help you. Again, how you use the fraction button when entering a calculation may vary depending on the brand of the calculator. However, the two most common methods are:

### 1) Numerator, fraction key, denominator

e.g. to enter $\frac{1}{2}$12, you would type: ### 2) FRACTION KEY, NUMERATOR, DENOMINATOR

This method is less common. However, some calculators (e.g. the one on the left above) will let you enter fractions this way. Once you press the fraction key, you can scroll to the box you want using the arrow keys and then fill in the numbers.

## Entering Mixed Fractions on a Calculator

You may have noticed that there are a lot of different functions in maths and making all these functions fit on a calculator is a pretty tricky task! One way they do this is by using second functions, which are the ones written in  tiny writing above the buttons on your calculator.

A mixed fraction is one of these second functions. So how do you enter one into the calculator?

Well, as mixed above, we need to use the SHIFT key, then press the fraction key like so: Again the order you press these and the number keys depends on your calculator, so it's worth asking your teacher to run you through it if you're not sure. Just a heads up- not all calculators and online devices work the same way, so it's important that you use the calculator you are allowed to use in your exams or tests often.  I have seen many students struggle in a test because they borrowed a friends calculator at the last minute and they don't know how to use it!

#### Worked Examples

##### Question 1

Using a calculator, evaluate $4\frac{4}{11}+1\frac{4}{9}$4411+149, expressing your answer as a mixed number in its simplest form.

##### Question 2

Using a calculator, evaluate $\frac{2}{5}+\frac{2}{3}\div\frac{3}{4}$25+23÷​34.

Maria is a sales assistant. She earns $\$293$$293 per week, plus a commission of \frac{2}{9}29 on anything she sells. Last week she sold \1377$$1377 of sofas.