Computers and calculators are the tools of modern mathematicians.Phone.jpg

At form 3 level you should be able to do all of the operations in the first eight topics covered so far WITHOUT using computers and calculators.

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



A typical graphical calculator
  • Try not to use your calculator for simple calculations involving adding, subtracting, dividing and multiplying whole numbers. e.g. 8 × 7 or 56 + 72.
  • Keep the instruction booklet that comes with the calculator. You will 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 which are common or similar on most calculators.

Basic Operations

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

e.g. Calculate 35 + 4 x 27 on a calculator. Press: calc3.gif calc5.gif calcadd.gif calc4.gif calcmult.gif calc2.gif calc7.gif calcequals.gif 143



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



The two brackets keys calcleftbracket.gif and calcrightbracket.gif are useful for calculations involving fractions.

e.g. Calculate  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 1262, press calc1.gif calc2.gif calc6.gif calcxsquared.gif calcequals.gif 15876

To calculate with an index greater than 2 use the button calcxpowery.gif e.g. To find 234, press calc2.gif calc3.gif calcxpowery.gif calc4.gif calcequals.gif 279841

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.

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 of rows.

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 45 for instructions and practice with these.