How_To_Be_Good_At_Math

156 CALCULATING •^ USING A CALCULATOR

Using a calculator

A calculator is a machine that can help us to work out the

answers to calculations. It’s important that we know how

to do calculations in our heads and with written methods,

but sometimes using a calculator can make calculating

quicker and easier.

The display shows

the numbers that

have been typed

in or the answer

Always double-check

your answer when you

are using a calculator,

because it’s easy to make

a mistake by accidentally

pressing the wrong keys.

Number keys

The main part of the calculator’s

keypad are the numbers 0 to 9.

We use these keys to enter the

numbers in a calculation.

Arithmetic keys

All calculators have keys for adding [+],

subtracting [−], multiplying [×], and dividing [÷].

If we wanted to calculate 14 × 27, we would

press [1], [4], [×], [2], [7], then [=].

ON and CLEAR key

This is the key we press to turn the

calculator on or to clear the display,

taking the value displayed back to zero.

Decimal point key

We press this key if we are calculating with

a decimal number. To enter 4.9, we press [4],

then the decimal point [. ], followed by [9].

Negative key

This key changes a positive number

into a negative number, or a negative

number into a positive number.

Calculator keys

Most calculators have the same basic keys,

just like this one. To use a calculator, we simply

type in the calculation we want to work out,

then press the [=] key. Let’s take a look at what

each key does.

ON

C

8

M

−

×

%

+

÷

√

MC M−MR +

7 9

4 5 6

1 2 3

0 =

. +/
−

156-157_Using_a_calculator.indd 156 29/02/2016 18:57