Computers and calculators are being used more and more by students, teachers and workers to help solve problems quicker.

Calculators can do many more types of calculations now than just a few years ago. For example, calculators can draw graphs, do algebra and carry out most statistics calculations.


Although calculators can do many types of calculation, at primary and lower secondary levels you should be able to do all of the operations in the ten topics covered so far WITHOUT using computers and calculators. Calculators are useful tools for checking your answers.

This section shows you how to do some of those calculations using these tools.



A Casio graphical calculator
  • Try not to use your calculator for simple calculations involving adding, subtracting, dividing and multiplying whole numbers and integers . e.g. 8 × 7 or -6 + 2.
  • Keep the instruction booklet that comes with the calculator. You may need it for the more complicated calculations and functions.
  • Estimate the answer to the calculation before you start. This is a good check in case you press the wrong keys.

There are many makes and types of calculators. The examples below use keys from the Casio fx-82TL which are common or similar to most calculators.

Basic Operations

Enter the numbers in the order they are given, then press calcequals.gif

Type of calculation
Calculator Keys
35 + 739 calc3.gif calc5.gif calcadd.gif calc7.gif calc3.gif calc9.gif calcequals.gif 774
965 − 349 calc9.gif calc6.gif calc5.gif calcsub.gif calc3.gif calc4.gif calc9.gif calcequals.gif 616
59 × 38 calc5.gif calc9.gif calcmult.gif calc3.gif calc8.gif calcequals.gif 2242
3510 ÷ 78 calc3.gif calc5.gif calc1.gif calc0.gif calcdiv.gif calc7.gif calc8.gif calcequals.gif 45


Calculators know about the order that calculations are carried out. i.e. BEDMAS

e.g. Calculate 56 + 3 × 85 on a calculator. Press:         311



Integer calculations are done using the calcneg.gif key for the negative integers.

Calculator Keys
5 + - 6 calc5.gif calcadd.gif calcneg.gif calc6.gif calcequals.gif -1
-3 × -2 calcneg.gif calc3.gif calcmult.gif calcneg.gif calc2.gif calcequals.gif 6


Some calculators do not round numbers. e.g. calc2.gif calcdiv.gif calc3.gif gives 0.666666666. This is calledtruncating.

Some calculators round numbers up or down e.g. calc2.gif calcdiv.gif calc3.gif gives 0.666666667. This is calledrounding.This number is rounded to 9 decimal places as there are 9 digits after the decimal point.

Rounding Rules

If the digit to the right of the rounded digit is between 0 and 4. The rounded digit stays the same.
If the digit to the right of the rounded digit is 5 or above. The rounded digit has ONE added.

Square roots


To find the square root of a number use this key calcsquareroot.gif e.g. To find the square root of 36, press calcsquareroot.gifcalc3.gif calc6.gif calcequals.gif 6

Square roots are often not whole numbers e.g. calcsquareroot.gif calc3.gif calc7.gif calcequals.gif 6.08276253



Some calculations involving fractions can be done on a calculator.

Fraction calculation
Calculator Keys
Change a fraction to a decimal. Write 58 as a decimal calc5.gif calcdiv.gif calc8.gif calcequals.gif 0.625
Change an improper fraction to a mixed number. Write 154 as a mixed number

calc1.gif calc5.gif calcfrac.gif calc4.gif calcequals.gif 3Fracdivider.gif3Fracdivider.gif4

This is 334
Do fraction calculations
(see Topic 49)
Calculate 14 + 58

calc1.gif calcfrac.gif calc4.gif calcadd.gif calc5.gif calcfrac.gif calc8.gifcalcequals.gif 7Fracdivider.gif 8

This is 78


Most calculators have a calcpercentage.gif key. On some calcualtors this means pressing the calcshift.gif key first.

Use these keys to write a fraction as a percentage.

e.g. calc5.gif calcdiv.gif calc8.gif calcshift.gif calcpercentage.gif 62.5


The two brackets keys calcleftbracket.gif and calcrightbracket.gif are useful for calculations involving more complicated fraction calculations.

e.g. Calculate calcfractionexa.gif Press: calc3.gif calc4.gif calcdiv.gif calcleftbracket.gif calc5.gif calc6.gif calcadd.gif calc3.gif calc9.gif calcrightbracket.gif calcequals.gif 0.351894736



There is a button for an index of 2 (squared) calcxsquared.gif e.g. To find 142, press calc1.gif calc4.gif calcxsquared.gif calcequals.gif 196

To calculate with an index greater than 2 use the button calcxpowery.gif e.g. To find 24, press calc2.gif calcxpowery.gif calc4.gif calcequals.gif 16


Spreadsheets Computer.gif

Computer programs such as Microsoft Office and Appleworks include a part called aspreadsheet
Spreadsheets can perform calculations using numbers and formulae arranged in rows and columns of cells
Words or numbers can be typed into the cells and calculations and other mathematical operations can be carried out. 
Other units in MathsOnline will contain spreadsheet exercises indicated by calcss6notes.gif


The spreadsheet on the left shows only 32 cells. Some spreadsheets have thousands of cells.
Each cell has its own label. 
The one highlighted is cell B3.

The letters are at the top of the columns.
The numbers are at the beginning ofrows.

To move around a spreadsheet use the cursor or keys such as the TAB, pg up, pg down (the arrow keys)

Many features of a spreadsheet can be changed (formatted) using various menu commands:

  • The columns can be made wider
  • The rows can be made higher
  • Numbers and text in a cell can be made bold, coloured or a different size and font
  • Numbers and text in a cell can be put on the left hand side, the right hand side or in the centre.


Spreadsheets do calculations differently from normal maths equations and calculators. To do a calculation you have to type in the EQUALS sign first. To do multiplication use the * key and for division use the / key.




The values in cells can also be used in calculations.



Numbers and words in both rows and columns can be sorted into order.
To do the sort shown below BOTH columns must be selected and the spreadsheet told to sort on the B column.



Most spreadsheets will produce graphs, such as pie graphs, line graphs, bar graphs and scattergraphs.
See Unit 44 for instructions and practice with these.