Lesson WHAT IS a number line

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Those who are great at mathematics are able to solve math problems by visualizing them. Number line helps to visualize the order of numbers.

A smaller number would show to the LEFT of the larger number. Example:

{{{ number_line( 300, -10, 10, 4.5, 7.2 ) }}}

Here, the number 4.5 is shown to the LEFT of 7.2. And, obviously, 4.5 is less than 7.2.

A number line is normally drawn as a "long arrow", with integer numbers marked on it for reference. Negative numbers are to the left of zero, and positive numbers are to the right of zero.

The distance from a smaller number to the greater number is the difference between the greater and the smaller number.

A number line is especially useful for learning to compare negative or positive numbers. A rule to remember is this:

<U>If a number is to the <B>left</B> of another, it is <B>smaller</B>. </U>

<U> if a number is to the <B>right</B> of another, it is <B>greater</B>. </U>

<H4>As you move from left to right, the numbers get larger</H4>

See this animation:
{{{cartoon (
  number_line( 500, -10, 10, -2 ),
  number_line( 500, -10, 10, -1),
  number_line( 500, -10, 10, 0 ),
  number_line( 500, -10, 10, 1 ),
  number_line( 500, -10, 10, 2 ),
  number_line( 500, -10, 10, 3 ),
  number_line( 500, -10, 10, 4 ),
  number_line( 500, -10, 10, 5 )
) 
}}}

<H4>As you move from right to left, the numbers get smaller</H4>

See this animation:
{{{cartoon (
  number_line( 500, -10, 10, 5 ),
  number_line( 500, -10, 10, 4 ),
  number_line( 500, -10, 10, 3 ),
  number_line( 500, -10, 10, 2 ),
  number_line( 500, -10, 10, 1 ),
  number_line( 500, -10, 10, 0 ),
  number_line( 500, -10, 10, -1 ),
  number_line( 500, -10, 10, -2 )
) 
}}}