How to read numbers, figures and mathematical expressions in English. Cardinal numbers Cardinal numbers refer to the size of a group. 1 2 3 4 zero (nought) one two three four 5 five 15 6 7 8 9 six seven eight nine 16 17 18 19 0 10 ten 11 12 13 14 eleven twelve thirteen fourteen fifteen (note "f", not "v") sixteen seventeen eighteen (only one "t") nineteen 20 twenty 30 thirty 40 forty (no "u") 50 fifty (note "f", not "v") 60 70 80 90 sixty seventy eighty (only one "t") ninety (note the "e") If a number is in the range 21 to 99, and the second digit is not zero, one should write the number as two words separated by a hyphen. 21 twenty-one 25 twenty-five 32 thirty-two 58 fifty-eight 64 sixty-four 79 seventy-nine 83 eighty-three 99 ninety-nine In English, the hundreds are perfectly regular, except that the word hundred remains in its singular form regardless of the number preceding it (nevertheless, one may on the other hand say "hundreds of people flew in", or the like) 100 one hundred 200 two hundred … … 900 nine hundred “English for Economists I” – Dr T.Tseligka-Gkaziani (Senior Teaching Fellow in ESP/EAP). University of Ioannina. 1 So too are the thousands, with the number of thousands followed by the word "thousand" 1,000 2,000 … 10,000 11,000 … 20,000 21,000 30,000 85,000 100,000 one thousand two thousand … ten thousand eleven thousand … twenty thousand twenty-one thousand thirty thousand eighty-five thousand one hundred thousand nine hundred and ninety-nine thousand (British English) 999,000 nine hundred ninety-nine thousand (American English) 1,000,000 one million 10,000,000 ten million Ordinal numbers Ordinal numbers refer to a position in a series. Common ordinals include: zeroth or noughth (see below) 1st first 0th 2nd second 3rd 4th 5th 6th 7th 8th 9th third fourth fifth sixth seventh eighth (only one "t") ninth (no "e") 10th tenth 11th eleventh twelfth (note "f", not 12th "v") 13th thirteenth 14th fourteenth 15th fifteenth 16th sixteenth 17th seventeenth 18th eighteenth 19th nineteenth 20th twentieth 30th thirtieth 40th fortieth 50th fiftieth 60th sixtieth 70th seventieth 80th eightieth 90th ninetieth Zeroth only has a meaning when counts start with zero, which happens in a mathematical or computer science context. “English for Economists I” – Dr T.Tseligka-Gkaziani (Senior Teaching Fellow in ESP/EAP). University of Ioannina. 2 Ordinal numbers such as 21st, 33rd, etc., are formed by combining a cardinal ten with an ordinal unit. 21st twenty-first 25th twenty-fifth 32nd thirty-second 58th fifty-eighth 64th sixty-fourth 79th seventy-ninth 83rd eighty-third 99th ninety-ninth [The sections on Cardinal and Ordinal Numbers have been adapted from: http://www.wikipedia.org) Addition, subtraction, multiplication, division x+y x–y x±y a y x:y x/y x (a+b) (a+b) x x plus y x minus y x plus [or] minus y a times y / a multiplied by y x divided by y x over y x times the sum of a and b open parenthesis a plus b close parenthesis multiplied by x Decimals 4.59 0.73 0.666… four point five nine zero point seven three zero point six recurring Fractions ½ 1/3 2/3 ¼ ¾ 1/5 one (or: a) half one (or: a) third two thirds one (or: a) quarter three quarters one(or: a) fifth For larger numbers we usually say: 3/7 three sevenths or three over seven 4/10 four tenths or four over ten 121/298 one hundred and twenty-one over two hundred and ninety-eight “English for Economists I” – Dr T.Tseligka-Gkaziani (Senior Teaching Fellow in ESP/EAP). University of Ioannina. 3 When fractions are found together with integer, they are read as follows: 8 3/8 eight and three eighths 5½ five and a half Powers, roots 5² 8³ 6ⁿ 7n 91/2 2 3 2 n 2 b ( x y)2 Equations 10+15=25 x≡y x y x≈y x≠y x >y x≥y x <y x≤y 0 x 1 0 x 1 Functions f ( x) f :S T x x f ( x ) f ( x ) dy dx f ( x ) x1 5 squared 8 cubed / 8 to the third power 6 to the ninth (power) / 6 to the power n / 6 to the n 7 to the minus nth power/ 7 to the power minus n/ 7 to the minus n 9 to (the) half power / the square root of 9 the square root of two the cube root of two The nth root of two the square root of the sum of a plus b x plus y all squared ten plus fifteen equals (or: is equal to) twenty-five x is identical with (or: to) y x is equivalent to y (set theory) x is nearly/approximately equal to y x is not equal to y x is greater (or: more) than y x is greater (or: more) or than or equal to y x is smaller (or: less) than y x is less (or: smaller) than or equal to y zero is less than x is less than one zero is less than or equal to x is less than or equal to one fx / f of x / the function f of x a function f from S to T x prime x double prime f prime x / f dash x / the first derivative of f with respect to x f double-prime x / f double-dash x / the second derivative of f with respect to x the derivative of y with respect to x the partial (derivative) of f with respect to x1 “English for Economists I” – Dr T.Tseligka-Gkaziani (Senior Teaching Fellow in ESP/EAP). University of Ioannina. 4 2 f ( x) x12 the second partial (derivative) of f with respect to x1 the integral from zero to infinity ∫∫ ∫∫∫ lim double integral triple integral the limit as x approaches zero lim the limit as x approaches zero from above lim the limit as x approaches zero from below ln y log x log y to the base e / natural log (of) y the log of x log10 x the common log of x log2 x the binary log of x/ the log of x to the base two 0 x 0 x 0 x 0 Linear Algebra AT A1 A transpose / the transpose of A A inverse / the inverse of A Sets x A x A A B A B A B A B x belongs to A / x is an element of A x does not belong to A / x is not an element of A A is contained in B / A is a subset of B A cap B / A meet B / A intersection B A cup B / A join B / A union B A cross B / the Cartesian product of A and B Logic x x pq pq there exists x for all x p implies q / if p, then q p if and only if q / p is equivalent to q Various 1….10 -3 ∞ [x] -x x one to ten minus [negative] 3 infinity x in brackets minus [negative] x x tilde “English for Economists I” – Dr T.Tseligka-Gkaziani (Senior Teaching Fellow in ESP/EAP). University of Ioannina. 5 X N (0,1) x xi xi the stochastic (random) variable X has the standard normal distribution. x bar x super i xi / x subscript i / x suffix i / x sub i x̂ x x hat / x wedge mod x / modulus x / absolute value of x x norm of x n! n factorial X N i 1 i the sum of X sub i from i equals 1 to N / the sum as i runs from 1 to N of the X sub i even vs odd numbers ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Acknowledgements Special thanks are owed to Athanasios Lapatinas (Lecturer, Dept.of Economics, Ioannina) for his useful contributions and review of the handout. “English for Economists I” – Dr T.Tseligka-Gkaziani (Senior Teaching Fellow in ESP/EAP). University of Ioannina. 6