APPROXIMATION OF NUMBERS

About "Approximation of numbers"

Approximation of numbers :

In our daily life we need to know approximate values or measurements.

David bought a Lap Top for $499.85. When he wants to convey this amount to others, he simply says that he has bought it for $500.

This is the approximate value which is given in hundreds only.

Daniel buys a pair of slippers for $19.99. This amount may be considered approximately as $20 for convenience.

A photo frame has the dimensions of 35.23 cm long and 25.91 cm wide. If we want to check the measurements with our ordinary scale, we cannot measure accurately because our ordinary scale is marked in tenths of centimeter only.

In such cases, we can check the length of the photo frame 35.2 cm to the nearest tenth or 35 cm to the nearest integer value.

In the above situations we have taken the approximate values for our convenience. This type of considering the nearest value is called ‘Rounding off’ the digits.

Thus the approximate value corrected to the required number of digits is known as ‘Rounding off’ the digits.

Approximation of numbers

Sometimes it is possible only to give approximate value, because

(a)  If we want to say the population of a city, we will be expressing only the approximate value say 30 hundred thousands or 25 hundred thousands and so on.

(b)  When we say the distance between two cities, we express in round number 350 km not 352.15 kilometers.

While rounding off the numbers we adopt the following principles.

(i)  If the number next to the desired place of correction is less than 5, give the answer up to the desired place as it is.

(ii)  If the number next to the desired place of correction is 5 and greater than 5 add 1 to the number in the desired place of correction and give the answer.

The symbol for approximation is usually denoted by 

Approximation of numbers - Illustrations

Approximation nearest to TEN :

Illustration :

Consider multiples of 10 before and after 521. ( i.e. 520 and 530 )

We find that 521 is nearer to 520 than to 530.

It has been illustrated in the picture given below.

Therefore, the approximate value of 521 is 520 in this case.

Approximation nearest to HUNDRED :

Illustration :

(i) Consider multiples of 100 before and after 521. ( i.e. 500 and 600 )

We find that 521 is nearer to 500 than to 600. So, in this case, the approximate value of 521 is 500.

(ii) Consider the number 625

Suppose we take the number line, unit by unit.

In this case, we cannot say whether 625 is nearer to 624 or 626, because it is exactly midway between 624 and 626. However, by convention we say that it is nearer to 626 and hence its approximate value is taken to be 626.

Suppose we consider multiples of 100, then 625 will be approximated to 600 and not 700

Some more examples

For the number 47,618

(a)  Approximate value correct to the nearest tens = 47,620

(b)  Approximate value correct to the nearest hundred = 47,600

(c)  Approximate value correct to the nearest thousand = 48,000

(d)  Approximate value correct to the nearest ten thousand = 50,000

Decimal Approximation

Illustration 1 :

Consider the decimal number 36.729

(a) It is 36.73 round to two decimal places. (Since the last digit 9 > 5, we add 1 to 2 and make it 3).

Therefore, 36.729 36.73 (Round to two decimal place)

(b) Look at the second decimal in 36.729, Here it is 2 which is less than 5, so we leave 7 as it is.

Therefore, 36.729 ≃ 36.7 (Round to one decimal place)

Illustration 2 :

Consider the decimal number 36.745

(a) It’s approximation is 36.75, round to two decimal places. Since the last digit is 5, we add 1 to 4 and make it 5.

(b) It’s approximation is 36.7, round to one decimal place. Since the second decimal is 4, which is less than 5, we leave 7 as it is.

36.745 ≃ 36.7

Illustration 3 :

Consider the decimal number 2.14829

(i) Approximate value rounded to one decimal place is 2.1

(ii) Approximate value rounded to two decimal places is 2.15

(iii) Approximate value rounded to three decimal places is 2.148

(iv) Approximate value rounded to four decimal places is 2.1483

Illustration 4 :

Round off the following numbers to the nearest integer:

(a) 288.29  (b) 3998.37  (c) 4856.795  (d) 4999.96

Solution :

(a)  288.29    288

(b)  3998.37   3998

(c)  4856.795  ≃  4857

(d) 4999.96  ≃  5000

After having gone through the stuff given above, we hope that the students would have understood "Approximation of numbers". 

Apart from the stuff given above, if you want to know more about "Approximation of numbers", please click here

Apart from "Approximation of numbers", if you need any other stuff in math, please use our google custom search here.

HTML Comment Box is loading comments...

ALGEBRA

Variables and constants

Writing and evaluating expressions

Solving linear equations using elimination method

Solving linear equations using substitution method

Solving linear equations using cross multiplication method

Solving one step equations

Solving quadratic equations by factoring

Solving quadratic equations by quadratic formula

Solving quadratic equations by completing square

Nature of the roots of a quadratic equations

Sum and product of the roots of a quadratic equations 

Algebraic identities

Solving absolute value equations 

Solving Absolute value inequalities

Graphing absolute value equations  

Combining like terms

Square root of polynomials 

HCF and LCM 

Remainder theorem

Synthetic division

Logarithmic problems

Simplifying radical expression

Comparing surds

Simplifying logarithmic expressions

Negative exponents rules

Scientific notations

Exponents and power

COMPETITIVE EXAMS

Quantitative aptitude

Multiplication tricks

APTITUDE TESTS ONLINE

Aptitude test online

ACT MATH ONLINE TEST

Test - I

Test - II

TRANSFORMATIONS OF FUNCTIONS

Horizontal translation

Vertical translation

Reflection through x -axis

Reflection through y -axis

Horizontal expansion and compression

Vertical  expansion and compression

Rotation transformation

Geometry transformation

Translation transformation

Dilation transformation matrix

Transformations using matrices

ORDER OF OPERATIONS

BODMAS Rule

PEMDAS Rule

WORKSHEETS

Converting customary units worksheet

Converting metric units worksheet

Decimal representation worksheets

Double facts worksheets

Missing addend worksheets

Mensuration worksheets

Geometry worksheets

Comparing  rates worksheet

Customary units worksheet

Metric units worksheet

Complementary and supplementary worksheet

Complementary and supplementary word problems worksheet

Area and perimeter worksheets

Sum of the angles in a triangle is 180 degree worksheet

Types of angles worksheet

Properties of parallelogram worksheet

Proving triangle congruence worksheet

Special line segments in triangles worksheet

Proving trigonometric identities worksheet

Properties of triangle worksheet

Estimating percent worksheets

Quadratic equations word problems worksheet

Integers and absolute value worksheets

Decimal place value worksheets

Distributive property of multiplication worksheet - I

Distributive property of multiplication worksheet - II

Writing and evaluating expressions worksheet

Nature of the roots of a quadratic equation worksheets

Determine if the relationship is proportional worksheet

TRIGONOMETRY

SOHCAHTOA

Trigonometric ratio table

Problems on trigonometric ratios

Trigonometric ratios of some specific angles

ASTC formula

All silver tea cups

All students take calculus 

All sin tan cos rule

Trigonometric ratios of some negative angles

Trigonometric ratios of 90 degree minus theta

Trigonometric ratios of 90 degree plus theta

Trigonometric ratios of 180 degree plus theta

Trigonometric ratios of 180 degree minus theta

Trigonometric ratios of 180 degree plus theta

Trigonometric ratios of 270 degree minus theta

Trigonometric ratios of 270 degree plus theta

Trigonometric ratios of angles greater than or equal to 360 degree

Trigonometric ratios of complementary angles

Trigonometric ratios of supplementary angles 

Trigonometric identities 

Problems on trigonometric identities 

Trigonometry heights and distances

Domain and range of trigonometric functions 

Domain and range of inverse  trigonometric functions

Solving word problems in trigonometry

Pythagorean theorem

MENSURATION

Mensuration formulas

Area and perimeter

Volume

GEOMETRY

Types of angles 

Types of triangles

Properties of triangle

Sum of the angle in a triangle is 180 degree

Properties of parallelogram

Construction of triangles - I 

Construction of triangles - II

Construction of triangles - III

Construction of angles - I 

Construction of angles - II

Construction angle bisector

Construction of perpendicular

Construction of perpendicular bisector

Geometry dictionary

Geometry questions 

Angle bisector theorem

Basic proportionality theorem

ANALYTICAL GEOMETRY

Analytical geometry formulas

Distance between two points

Different forms equations of straight lines

Point of intersection

Slope of the line 

Perpendicular distance

Midpoint

Area of triangle

Area of quadrilateral

Parabola

CALCULATORS

Matrix Calculators

Analytical geometry calculators

Statistics calculators

Mensuration calculators

Algebra calculators

Chemistry periodic calculator

MATH FOR KIDS

Missing addend 

Double facts 

Doubles word problems

LIFE MATHEMATICS

Direct proportion and inverse proportion

Constant of proportionality 

Unitary method direct variation

Unitary method inverse variation

Unitary method time and work

SYMMETRY

Order of rotational symmetry

Order of rotational symmetry of a circle

Order of rotational symmetry of a square

Lines of symmetry

CONVERSIONS

Converting metric units

Converting customary units

WORD PROBLEMS

HCF and LCM  word problems

Word problems on simple equations 

Word problems on linear equations 

Word problems on quadratic equations

Algebra word problems

Word problems on trains

Area and perimeter word problems

Word problems on direct variation and inverse variation 

Word problems on unit price

Word problems on unit rate 

Word problems on comparing rates

Converting customary units word problems 

Converting metric units word problems

Word problems on simple interest

Word problems on compound interest

Word problems on types of angles 

Complementary and supplementary angles word problems

Double facts word problems

Trigonometry word problems

Percentage word problems 

Profit and loss word problems 

Markup and markdown word problems 

Decimal word problems

Word problems on fractions

Word problems on mixed fractrions

One step equation word problems

Linear inequalities word problems

Ratio and proportion word problems

Time and work word problems

Word problems on sets and venn diagrams

Word problems on ages

Pythagorean theorem word problems

Percent of a number word problems

Word problems on constant speed

Word problems on average speed 

Word problems on sum of the angles of a triangle is 180 degree

OTHER TOPICS 

Profit and loss shortcuts

Percentage shortcuts

Times table shortcuts

Time, speed and distance shortcuts

Ratio and proportion shortcuts

Domain and range of rational functions

Domain and range of rational functions with holes

Graphing rational functions

Graphing rational functions with holes

Converting repeating decimals in to fractions

Decimal representation of rational numbers

Finding square root using long division

L.C.M method to solve time and work problems

Translating the word problems in to algebraic expressions

Remainder when 2 power 256 is divided by 17

Remainder when 17 power 23 is divided by 16

Sum of all three digit numbers divisible by 6

Sum of all three digit numbers divisible by 7

Sum of all three digit numbers divisible by 8

Sum of all three digit numbers formed using 1, 3, 4

Sum of all three four digit numbers formed with non zero digits

Sum of all three four digit numbers formed using 0, 1, 2, 3

Sum of all three four digit numbers formed using 1, 2, 5, 6