Mathematics dictionary

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answer – The solution to a mathematical calculation or problem. ... curved side – A rounded line that is not straight. D .... should be. You round-off each number to the nearest ten or hundred. .... kilometre is about 3 blocks of houses, about from the school .... base are the same shape as the base, but get smaller and smaller ...
Focus on Primary Maths

Focus on Primary Maths

Mathematics dictionary 1

Focus on Primary Maths

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Focus on Primary Maths

2 – digit number – A number with 2 digits; it has a tens digit and a units/ones digit. For example 67 is a 2 – digit number: 67 = 60 + 7 3 – digit number – A number with 3 digits; it has a hundreds digit, a tens digit and a units/ones digit. For example 567 is a 3 – digit number: 567 = 500 + 60 + 7 4 – digit number – A number with 4 digits; it has a thousands digit, a hundreds digit, a tens digit and a units/ones digit. For example 567 is a 3 – digit number: 567 = 500 + 60 + 7

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A a.m. – Ante meridiem, before noon. accurately – As close to correct as you can. add – Combine or join. Find the total of two or more numbers. The operation symbol is +: 50 + 70 = 120 add – Other words for add: join, combine, plus, increase, altogether, in total, sum adding and subtracting strategy – Breaking up, filling up tens, and compensating. 4

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add on – This is the strategy for adding/subtracting. You break down the smaller number. You start with the bigger number and add on the hundreds, tens and units of the smaller number: 156 + 234 = 234 + 100 + 50 + 6 addition – Sum, increase by, more than, plus, all together, combine, in total. altogether – In total, combined. This can imply add, but not always. For example, there are 3 cars, how many wheels are there altogether. 4 × 3 = 12 cars. analogue clock – A clock with hands. 5

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ante meridiem (a.m.) – Before noon. In the morning. answer – The solution to a mathematical calculation or problem. approximately – about; almost; nearly area – The amount of space the surface of an object covers. arrange – To position or place. ascending – Going up, or going from smallest to biggest.

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B bar graph – A chart to display information. It uses vertical or horizontal bars. The length of each bar shows the amount of something. beaker – A tall cup, usually with a lip and no handle. bigger than or greater than – more than. The symbol is >. breaking down – A strategy for working with big numbers. It is when a big number is separated into its parts. This can be done using a number sentence with adding or multiplying. For 7

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example, 542 can be broken up into 500 + 40 + 2 or 10 can be broken up into 2 × 5. breaking up – The same as breaking down.

C capacity – The capacity of a container is the maximum amount of something that can fit into it. cell – Small square in a grid. centi – 100 equal parts. 8

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centimetre – A unit for length. There are 100 centimetres in one metre. One centimetre is about as long as your finger nail. cent – A unit for money. There are 100 cents in one Rand. century– A unit for time. There are 100 years in one century. change – The amount of money given back to you when you buy something. change – Transform, do not stay the same.

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check – Think again carefully to be sure that your answer is correct. Try use a different method. chunking – A strategy for division which uses repeated subtraction. 80 ÷ 6 is the same as “how many 6’s are in 80?” Choose sensible chunks of groups of 6, to subtract from 80. You keep track of how many groups of 6 you need to subtract from 80 to get to zero. circular – Rounded. Shaped like a circle. A smooth curve around a point. circumference – Length once around the curved side of a circle. 10

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collect – Look for, find and keep. column – Things or numbers in a straight line from top to bottom. It can be in a table. A column is vertical. compare – Describe what is the same, and what is different about two or more things. For example to compare 2 and 6: 2 and 6 are both even numbers. They are both whole 1-digit numbers. 2 is smaller than 6. The difference between 2 and 6 is 4. compensate – Put back what has been taken, or take away what has been added. If you add 4 to get a multiple of ten, then you must take it away again from the other number for 11

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the number sentence to stay the same: 56 + 27 = (56 + 4) + (27 – 4) = 60 + 23. conclude – Summarise what was found, and therefore what should happen because of the research. convert – To change. To convert from kilograms to grams means to change from measuring in kilograms, to measuring in grams. converting units – Changing the unit used for measuring. The same object is measured, but the units used for measuring are different.

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co – ordinates – Grid reference. Two numbers which show how far across, and how far up a point is on a grid. count on – Start with a number then increase using equal jumps. Count on in 3s from 10 = 10; 13; 16; 19; … cube – A 3D object shaped like a box. It has the same measurements in all directions: height = width = length. curved side – A rounded line that is not straight.

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data – Information collected by a researcher. day – Unit for measuring time. It is the time taken for the earth to spin once on its axis. There are 24 hours in 1 full day. describe – Explain in words what you see or feel. deca – Ten in Greek. decagon – A polygon with 10 sides decade – 10 years decimal – A place value system using tens and multiples of ten. 14

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decrease – Make smaller or subtract a number bigger than zero. decrease by a number of times – Make smaller or divide by a number bigger than 1. decompose – break down a number using multiples of ten. Decompose 365 is 300 + 60 + 5. denominator – The number at the bottom of a fraction. The denominator defines the fraction name: denominator 2 is halves, denominator 3 is thirds, etc. descending – Going down, or going from biggest to smallest. 15

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descending order – From biggest to smallest. device – instrument or tool diagonal – A line joining two opposite points of a 2D – shape. diagonal – A straight line that is not horizontal or vertical. digit – The number symbols used to write all numbers. There are only 10 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8 and 9. digital clock – Clock that has no hands, just digits. dimension – Size or measurement. 3D shapes have 3 dimensions: height, length and width. 16

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discount – Amount that a price is reduced or less than the normal selling price. divide – Operation with two meanings. (÷) – 15 ÷ 3 = ‘15 divided by 3’. It means ‘15 shared equally between 3’ (each gets 5), or ‘how many 3s are in 15?’ (there are 5 groups of 3.) It is the same as a fraction: 15 ÷3 = 1 third of 15. divide (words/phrases for division) – ‘Divide’, ‘quotient’, ‘share equally’, ‘equal groups’, ‘how many in each?’, ‘how many do each get?’, ‘how much in each one?’, ‘the price all together is this, so how much does each one cost?’, ratio, rate. 17

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dividend – The number that you are dividing. This is the input in a division function machine. In 20 ÷ 5 = 4, the dividend is 20. The dividend is the same as the numerator if you write division as a fraction. divisor – The number you are dividing by. This is the rule in a division function machine. In 20 ÷ 5 = 4, the divisor is 5. The divisor is the same as the denominator if you write division as a fraction. double – Multiply by two. Add the number to itself: Double 4 = 4 + 4. Or count the ones in that number of pairs: Double 4 = 2 + 2 + 2 + 2. dozen – A group of twelve. A dozen eggs means 12 eggs. 18

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E edge – the straight line on a 3D object where 2 flat surfaces (faces) meet. efficient chunking – A strategy for division which uses repeated subtraction or addition. Use a clue – board consisting of these inputs: 1, 2, 4, 8, 10 (and if needed 5). This gives information about sensibly – sized ‘chunks’ to subtract from the dividend.

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eighth – When you divide 1 whole into 8 equal parts you get 8 eighths. eighth – Position number 8 in a list or race. enlarge – Make bigger keeping all the proportions the same. Every dimension is multiplied by the same number. It is the opposite of reduce. equals – The same as. The symbol is =. Equals does not mean ‘find the answer’. equivalent number sentences – Two number sentences are equivalent if they have the same solution: □ + 24 = 100 is equivalent to □ = 100 – 24 20

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equivalent – ‘Equal to’, ‘the same as’. Equivalent fractions have the same value. 1 half has the same value as 2 quarters. estimate the answer – Calculate more or less what the answer should be. You round-off each number to the nearest ten or hundred. The calculation is then easier and you get closer to the answer. estimate a measurement – Say what you think the measurement and the units will be, before you measure using an instrument. expand – To make bigger or longer. 21

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expanded notation – Breaking up a number into multiples of 10 (ones, tens, hundreds etc.), for example, 346 = 300 + 40 + 6 express – Describe expression – A description. It is like a phrase in English. “The black dog” is a phrase or expression in English. “4 + 6” is an expression in mathematics. extend – Make longer, carry on or continue.

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face – The flat surface of a 3D object. factorise – To write as a product of factors. To factorise 12: 12 = 12 × 1 = 2 × 6 = 3 × 4. factors – Factors of a number are the pairs of whole numbers that can be multiplied together to get that number as an output. The factors of 12 are 1 and 12, 2 and 6, and 3 and 4, because 1 × 12 = 12, and 2 × 6 = 12, and 3 × 4 = 12. family – Group that shares something in common. The members of the group are similar or related. fill up the tens – A strategy for adding/subtracting. You get to the nearest ten or hundred, so that the numbers are easier to 23

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work with: 77 + 37 = 80 + 34. If you add 3 to get to 80, then you must subtract 3 to keep the number sentence the same (compensating). fifth – Position number 5 in a list or race. fifth – When you divide 1 whole into five equal parts, you get 5 fifths. When you divide a group into five equal parts, each group is 1 fifth of the group. first – Position number 1 in a list or race. flow diagram – A picture with inputs and outputs to show a mathematical rule. It is also called a function machine. fluid – Another word for ‘liquid’. 24

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fraction – Equal parts of 1 whole. The whole can be 1 thing, or a group of things. 2 thirds is a fraction. The whole is divided into 3 equal parts. 2 of these parts is 2 thirds of the whole. A fraction is also a whole number divided by another whole number. 2 thirds is 2 ÷ 3. fraction wall – Wall showing the size of common fractions. The length of the row of bricks show the position of the fraction on a number line, e.g. 3 quarters is 3 bricks that are each 1 quarter long. function – A mathematical rule that changes each input to give only one output. ‘+10’ is a function. If the input is 6, the only output it can be is 16. But ‘find the factors’ is not a 25

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function. If the input is 6, the outputs can be 1, 6, 2 or 3. This is not a function.

G general rule – A rule that explains how to predict any output (if you know the input) for a pattern. gram (g) – Mass is measured in grams. This is a standard unit. One gram is very light. One small sweet or a tea bag has a mass of about 1 or 2 grams.

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grid – Squares or cells arranged in vertical columns and horizontal rows. group – Collection or set of objects, or numbers. Also the process of forming sets or grouping, used for division and subtraction.

H half – When you divide a whole into 2 equal parts you get halves. halve – The process of dividing into 2 equal parts. 27

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height (h) – This is how tall or high an object is, and is usually measured vertically (from bottom to top, or from the ground upwards). hept – Seven in Greek. heptagon – A polygon with seven sides. hex – Six in Greek. hexagon – A polygon with six sides. horizontal – A line going from left to right, or right to left. Across, with the horizon. hour – A unit for measuring time. There are 24 hours in one full day. 28

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I increase – Make bigger, add a number bigger than zero. increase by a number of times – Make bigger, multiply by a number bigger than one. identical – Exactly the same. Equal in every way. ingredient – One type of food that is needed for a recipe. input – Something that is put in or given. Inputs go into a function machine, the rule changes them; and they become outputs. 29

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interpret – Make sense of, understand or explain. inverse – The reverse or opposite of a mathematical rule. Addition and subtraction are inverses. The inverse of the rule + 3 is – 3. Multiplication and division are inverses. The inverse of the rule × 2 is ÷ 2.

J join – Put together joining side – sides in a polygon that touch, meeting at a point. Can be called adjacent side.

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K kilo – One thousand. kilogram (kg) – Unit for measuring mass. 1 kg is 1 000 g. A medium – sized bag of sugar or a very large tub of margarine has a mass of 1 kg. kilometre (km) – Unit for measuring length. 1 km = 1 000 m. A kilometre is about 3 blocks of houses, about from the school to the nearby shops.

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L leap year – Every fourth year which has 366 days. The extra day is the 29th of February. length (l) – The longest side of an object. How long an object is. Length is also the measurement of any straight line. less than – Smaller than. This is an instruction or rule to subtract. This is a subtracting problem. 2 less than 10 is 8: 10 – 2 = 8= 2 less – Smaller. 32

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line of symmetry – A line which divides a 2D shape into two halves which are a mirror image of each other. litres (ℓ) – The standard unit for measuring liquids. locate – find

M mass – This is how heavy something is, and is measured in grams or kilograms. 33

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maximum – Biggest; the most. method – A way of writing down a calculation to show your working. metre (m) – The standard unit for measuring length. A door is 2 metres high. midday – The middle of the day when the sun is highest and it is lightest. Noon. midnight – The middle of the night when it is darkest. midway – Exactly in the middle. 34

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milli – 1 000 equal parts. millilitres (mℓ) – A unit for measuring small amounts of liquids. There are 1 000 millilitres in one litre. One teaspoon holds 5 mℓ of liquid. millimetre (mm) – A unit for measuring small lengths. One millimetre is about as wide as the white part of your finger nail. One millimetre is about the width of a match stick. 1 000 mm = 1 m. minimum – The least.

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minute – A unit for measuring time. There are 60 minutes in one hour. It takes about a minute to count: 1 second, 2 seconds, … 60 seconds. multiple – A multiple of a number is the answer to a number sentence, where that number is multiplied by a whole number. The multiples of 4 are 4; 8; 12; 16; …etc multiplication (words/phrases for multiplication) – ‘Groups of’, ‘product’, ‘multiply’, ‘times’, ‘repeated groups’, ‘each time’, ‘each get’, ‘again and again’, ‘if 1 thing costs this amount, how much do 10 things cost? multiply or times (×) – 4 × 3 = ‘4 times 3’ or ‘4 multiplied by 3’. This means ‘4 groups of 3’ = 3 + 3 + 3 + 3, or ‘4 repeated 3 36

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times’ = 4 + 4 + 4. Multiplication is the same as adding again and again (repeated addition).

N narrow – Thin; not wide. A small width. natural numbers – Counting numbers (1, 2, 3, 4, 5, etc.). net – The flat shape that can be folded to make a 3 – D object.

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nineth – When you divide 1 whole into 9 equal parts you get nineths. nineth – Position number 9 in a list or race. nonagon – A polygon with 9 sides. not equals or unequal – Not the same. The symbol is ≠. notation – writing. number expression – A description using digits and operations. It shows a plan of how to calculate. 39 + 1 + 5 is an expression that shows a plan of how to add 6 to 39. 38

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number line – A straight line with numbers arranged in order on it. The whole numbers are equally spaced. It can be drawn or imagined (and need not be neat or even). number sentence – A mathematical sentence with a left side and right side. In the middle is = or ≠ or > or