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Number Line Basics Song – Learn Numbers – Learning Upgrade
Number Line Basics Song – Learn Numbers – Learning Upgrade
Published: 2016/02/10
Channel: Learning Upgrade
Placing Numbers on a Number Line
Placing Numbers on a Number Line
Published: 2010/09/02
Channel: deandreasmith2
How To Read Number Lines.mov
How To Read Number Lines.mov
Published: 2012/08/31
Channel: tenframe
Very Basics of Graphing Inequalities (on a number line)
Very Basics of Graphing Inequalities (on a number line)
Published: 2013/05/31
Channel: MathWOEs
Counting 1 - 10 on the Number Line With Froggy
Counting 1 - 10 on the Number Line With Froggy
Published: 2011/10/03
Channel: Complabteacher
Fractions on a Number Line - Mr. Pearson Teaches 3rd Grade
Fractions on a Number Line - Mr. Pearson Teaches 3rd Grade
Published: 2016/01/20
Channel: Mr. Pearson Teaches 3rd Grade
number line addition by Peter Weatherall
number line addition by Peter Weatherall
Published: 2008/11/13
Channel: Peter Weatherall
Number line addition for kindergarten / 1st grade math
Number line addition for kindergarten / 1st grade math
Published: 2015/07/10
Channel: Math Mammoth
Number Line Word Problem - 1st and 2nd grade
Number Line Word Problem - 1st and 2nd grade
Published: 2014/12/17
Channel: Math & Learning Videos 4 Kids
Learn Addition Using Number Line | Elementary Maths Concept for Kids | Addition | Part 4
Learn Addition Using Number Line | Elementary Maths Concept for Kids | Addition | Part 4
Published: 2016/08/26
Channel: Periwinkle
Open Number Lines 2nd Grade
Open Number Lines 2nd Grade
Published: 2015/10/29
Channel: Lindsey Weems - Goldsberry
Number Line - Numberphile
Number Line - Numberphile
Published: 2013/07/30
Channel: Numberphile
Rational Numbers on a Number Line - Part 2
Rational Numbers on a Number Line - Part 2
Published: 2014/12/18
Channel: Don't Memorise
Number Line Song!
Number Line Song!
Published: 2013/12/13
Channel: Jennifer Fernbach
Fractions on Number Lines - v2
Fractions on Number Lines - v2
Published: 2012/09/18
Channel: mikkadamia
Rational Numbers on a Number Line - Part 1
Rational Numbers on a Number Line - Part 1
Published: 2014/12/18
Channel: Don't Memorise
Multiplying With a Number Line
Multiplying With a Number Line
Published: 2014/04/04
Channel: Ramy Melhem
Math Antics - Negative Numbers
Math Antics - Negative Numbers
Published: 2014/09/24
Channel: mathantics
Number Line Introduction
Number Line Introduction
Published: 2015/02/08
Channel: Mathematics is Fun
How to plot inequalities on a number line | Pre-Algebra | Khan Academy
How to plot inequalities on a number line | Pre-Algebra | Khan Academy
Published: 2013/07/16
Channel: Khan Academy
Numberline (little extra bit)
Numberline (little extra bit)
Published: 2013/08/19
Channel: BradyStuff
How do we Plot Root 2 on a Number Line?
How do we Plot Root 2 on a Number Line?
Published: 2014/12/19
Channel: Don't Memorise
Number line subtraction by Peter Weatherall
Number line subtraction by Peter Weatherall
Published: 2008/11/13
Channel: Peter Weatherall
Adding and subtracting on number line word problems | Early Math | Khan Academy
Adding and subtracting on number line word problems | Early Math | Khan Academy
Published: 2015/06/02
Channel: Khan Academy
Rational Numbers on a Number Line - Part 3
Rational Numbers on a Number Line - Part 3
Published: 2014/12/18
Channel: Don't Memorise
Represent √7 on the number line.
Represent √7 on the number line.
Published: 2017/04/21
Channel: Gyan Abhiyan
Learn Grade 1 - Maths - Number line
Learn Grade 1 - Maths - Number line
Published: 2011/10/17
Channel: KidsClassroom
Second Grade Open Number Line Subtraction
Second Grade Open Number Line Subtraction
Published: 2015/09/18
Channel: Archway Glendale
Ordering Fractions on a Number Line
Ordering Fractions on a Number Line
Published: 2014/11/06
Channel: Laura Stegmann
Division Using A Number Line
Division Using A Number Line
Published: 2014/03/24
Channel: Ramy Melhem
Representing Fractions on Number line
Representing Fractions on Number line
Published: 2013/09/03
Channel: MathsSmart
Representing rational number on number line
Representing rational number on number line
Published: 2012/12/25
Channel: Anita Govilkar
Representing Irrational numbers (√2, √3) on the number-line (Part-3)
Representing Irrational numbers (√2, √3) on the number-line (Part-3)
Published: 2012/04/23
Channel: dostotussigreatho
Decimals on a Number Line
Decimals on a Number Line
Published: 2014/01/12
Channel: Michele Hearn
How to Represent Fractions with Different Denominators on Number Line
How to Represent Fractions with Different Denominators on Number Line
Published: 2016/12/02
Channel: Anil Kumar
Graphing Inequalities on a Number Line
Graphing Inequalities on a Number Line
Published: 2015/11/06
Channel: Stacey Miller
Represent √10, √11, √12 on the number line.
Represent √10, √11, √12 on the number line.
Published: 2017/04/22
Channel: Gyan Abhiyan
How to Represent Improper Fraction into Number Line
How to Represent Improper Fraction into Number Line
Published: 2012/07/04
Channel: IMA Videos
Subtracting Integers on a Number Line
Subtracting Integers on a Number Line
Published: 2014/09/08
Channel: Mary Anne Freitas
Rational number on a number line
Rational number on a number line
Published: 2011/06/01
Channel: smartschoolonline
Plotting Irrational Numbers on a Number Line
Plotting Irrational Numbers on a Number Line
Published: 2014/04/17
Channel: Mike Buboltz
Represent root x on a Number Line - Part 1
Represent root x on a Number Line - Part 1
Published: 2014/12/19
Channel: Don't Memorise
Locating square root of 5 on number line - Maths/ ISCE/ CBSE/ICSE/ NCERT
Locating square root of 5 on number line - Maths/ ISCE/ CBSE/ICSE/ NCERT
Published: 2015/04/21
Channel: Arinjay Jain Academy
Decimals and fractions on a number line | Decimals | Pre-Algebra | Khan Academy
Decimals and fractions on a number line | Decimals | Pre-Algebra | Khan Academy
Published: 2011/01/19
Channel: Khan Academy
Adding fractions with number lines
Adding fractions with number lines
Published: 2011/10/24
Channel: Duane Habecker
Absolute value and number lines | Negative numbers and absolute value | Pre-Algebra | Khan Academy
Absolute value and number lines | Negative numbers and absolute value | Pre-Algebra | Khan Academy
Published: 2010/05/06
Channel: Khan Academy
Plotting basic fractions on the number line | Fractions | Pre-Algebra | Khan Academy
Plotting basic fractions on the number line | Fractions | Pre-Algebra | Khan Academy
Published: 2013/08/02
Channel: Khan Academy
Double digit addition with open number line
Double digit addition with open number line
Published: 2013/11/07
Channel: Rachel Moss
Placing positive and negative decimals on a number line | Decimals | Pre-Algebra | Khan Academy
Placing positive and negative decimals on a number line | Decimals | Pre-Algebra | Khan Academy
Published: 2013/08/12
Channel: Khan Academy
Graphing Inequalities on a Number Line
Graphing Inequalities on a Number Line
Published: 2008/03/15
Channel: Marc Whitaker
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WIKIPEDIA ARTICLE

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In basic mathematics, a number line is a picture of a graduated straight line that serves as abstraction for real numbers, denoted by . Every point of a number line is assumed to correspond to a real number, and every real number to a point.[1]

The integers are often shown as specially-marked points evenly spaced on the line. Although this image only shows the integers from −9 to 9, the line includes all real numbers, continuing forever in each direction, and also numbers not marked that are between the integers. It is often used as an aid in teaching simple addition and subtraction, especially involving negative numbers.

The number line

In advanced mathematics, the expressions real number line, or real line are typically used to indicate the above-mentioned concept that every point on a straight line corresponds to a single real number, and vice versa.

Drawing the number line[edit]

A number line is usually represented as being horizontal, but in a Cartesian coordinate plane the vertical axis (y-axis) is also a number line.[2] According to one convention, positive numbers always lie on the right side of zero, negative numbers always lie on the left side of zero, and arrowheads on both ends of the line are meant to suggest that the line continues indefinitely in the positive and negative directions. Another convention uses only one arrowhead which indicates the direction in which numbers grow.[2] The line continues indefinitely in the positive and negative directions according to the rules of geometry which define a line without endpoints as an infinite line, a line with one endpoint as a ray, and a line with two endpoints as a line segment.

Comparing numbers[edit]

If a particular number is farther to the right on the number line than is another number, then the first number is greater than the second (equivalently, the second is less than the first). The distance between them is the magnitude of their difference—that is, it measures the first number minus the second one, or equivalently the absolute value of the second number minus the first one. Taking this difference is the process of subtraction.

Thus, for example, the length of a line segment between 0 and some other number represents the magnitude of the latter number.

Two numbers can be added by "picking up" the length from 0 to one of the numbers, and putting it down again with the end that was 0 placed on top of the other number.

Two numbers can be multiplied as in this example: To multiply 5 × 3, note that this is the same as 5 + 5 + 5, so pick up the length from 0 to 5 and place it to the right of 5, and then pick up that length again and place it to the right of the previous result. This gives a result that is 3 combined lengths of 5 each; since the process ends at 15, we find that 5 × 3 = 15.

Division can be performed as in the following example: To divide 6 by 2—that is, to find out how many times 2 goes into 6—note that the length from 0 to 2 lies at the beginning of the length from 0 to 6; pick up the former length and put it down again to the right of its original position, with the end formerly at 0 now placed at 2, and then move the length to the right of its latest position again. This puts the right end of the length 2 at the right end of the length from 0 to 6. Since three lengths of 2 filled the length 6, 2 goes into 6 three times (that is, 6 ÷ 2 = 3).

Portions of the number line[edit]

The closed interval [a,b].

The section of the number line between two numbers is called an interval. If the section includes both numbers it is said to be a closed interval, while if it excludes both numbers it is called an open interval. If it includes one of the numbers but not the other one, it is called a half-open interval.

All the points extending forever in one direction from a particular point are together known as a ray. If the ray includes the particular point, it is a closed ray; otherwise it is an open ray.

Extensions of the concept[edit]

Scaling[edit]

A log-log plot of y = x (blue), y = x2 (green), and y = x3 (red).
Note the logarithmic scale markings on each of the axes, and that the log x and log y axes (where the logarithms are 0) are where x and y themselves are 1.

It is sometimes convenient to scale the numbers on the number line with a logarithmic scale, using scientific notation. For example, the number one inch to the right of 0 might be 1, then the number one inch farther to the right would be 101 (=10), then one inch to the right of that would be 102 (=100), then 1000, then 10,000, etc. This approach is useful, for example, in illustrating a sequence of events in the history of the universe or of evolution, or in comparing distances to various stars.

Combining number lines[edit]

A line drawn through the origin at right angles to the real number line can be used to represent the imaginary numbers. This line, called imaginary line, extends the number line to a complex number plane, with points representing complex numbers.

Alternatively, one real number line can be drawn horizontally to denote potential values of one real number, commonly called x, and another real number line can be drawn vertically to denote potential values of another real number, commonly called y. Together these lines form what is known as the Cartesian coordinate system, and any point in the Cartesian plane denotes the values of a pair of real numbers. Further, the Cartesian coordinate system can itself be extended by visualizing a third number line "coming out of the screen (or page)", measuring a third variable called z. Positive numbers are closer to the viewer's eyes than the screen is, while negative numbers are "behind the screen"; larger number are farther from the screen. Then any point in the three-dimensional space that we live in represents the values of a trio of real numbers.

See also[edit]

References[edit]

  1. ^ Stewart, James B.; Redlin, Lothar; Watson, Saleem (2008). College Algebra (5th ed.). Brooks Cole. pp. 13–19. ISBN 0-495-56521-0. 
  2. ^ a b Introduction to the x,y-plane "Purplemath" Retrieved 2015-11-13

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