HOTmaths dictionary

This illustrated dictionary offers free access to over several hundred mathematical symbols, terms and definitions from the early secondary syllabus.

Select any letter to see examples of mathematical terms with clear explanations and helpful diagrams.

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SYMBOLS A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

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Term Definition undecagon an eleven-sided plane figure with straight sides Regular undecagon Irregular undecagon

Related links: 2D shapes — Plane shapes

© 2007 HOTmaths Pty Ltd

Term Definition uniform having all the parts or elements the same; sharing the same characteristics

Related links: Measuring solids — Volume of any prism 3D shapes — Classifying solids

© 2007 HOTmaths Pty Ltd

Term Definition union (sets) the combination of all elements from two or more sets shown by the symbol Example If A = {1, 2, 3} and B = {2, 3, 4} then A  B = {1, 2, 3, 4}

Related links: Set theory — Applying Venn diagrams Set theory — Set relationships and Venn diagrams

© 2007 HOTmaths Pty Ltd

Term Definition unit (measurement) standard quantity used for measurement Example A kilometre (km) is a unit of measurement for length. A millilitre (mL) is a unit of measurement for capacity. A gram (g) is a unit of measurement for weight.

Related links: Fractions — This as a fraction of that Algebra — Patterns on the number grid Length, perimeter and area — Units of length Measuring solids — Volume Measuring solids — Volume of rectangular prisms Measuring solids — Capacity Measuring solids — Mass Time — Time measurements 3D shapes — Drawing solids Pythagoras' theorem — Length of the hypotenuse Representing data — Line, conversion and step graphs Applying percentages — One amount as a percentage of another Circles and cylinders — Volume of a cylinder The number plane — Plotting positive integers Ratios and rates — Rates

© 2007 HOTmaths Pty Ltd

Term Definition unit (place value) place value for ones Example In the number 365, the digit 5 is in the units column, which means 5 ones.

Related links: Whole numbers — Place value and expanded notation Ratios and rates — Using ratios

© 2007 HOTmaths Pty Ltd

Term Definition unitary method way of solving a problem by reducing one of the units to 1 Example If I earned $80 interest on my savings invested at 4%, what amount did I originally invest? First find 1% then find 100%: 4% of savings = $80 1% of savings = $80 ÷ 4 = $20 100% of savings = $20 × 100 = $2000

Related links: Ratios and rates — Using ratios

© 2007 HOTmaths Pty Ltd

Term Definition universal set includes all possible elements for a given situation The symbol U represents the universal set. In Venn diagrams, the universal set is shown by a rectangle that surrounds the other sets.

Related links: Set theory — Applying Venn diagrams

© 2007 HOTmaths Pty Ltd

Term Definition unknown a pronumeral used in an equation to represent a quantity that is to be determined by solving the equation

Related links: Algebra — Algebra pictures Algebra — Words into algebra Angles — Angle theorems Equations and inequalities — Working backwards Equations and inequalities — Guess, check and improve Equations and inequalities — Equations to solve problems Equations and inequalities — Equations and formulas Manipulating algebra — Factorising Manipulating algebra — Algebraic fractions Congruent and similar shapes — Scale factor

© 2007 HOTmaths Pty Ltd

Term Definition unlike signs signs that are not the same Example + − are two unlike signs

Related links: Integers — Multiplying integers Integers — Dividing integers Algebra — Substitution

© 2007 HOTmaths Pty Ltd

Term Definition unlike terms terms that do not have exactly the same pronumerals and exponents Examples 2mn and 4m and −7m2 are all unlike terms. 4p3 and −3k3 and k2 are all unlike terms.