PRE ALGEBRA NUMBER LINE

ABSOLUTE VALUE - INTEGERS

To find the absolute value of a number, make it a positive number.
When writing the symbol for absolute value place the number in brackets ||
|6| = 6

and,

|3| + |-3| = 6

THE NUMBER LINE

The number line is useful when learning about absolute value of numbers (integers)
The number line has at center 0, to its left negative numbers and to right of 0 positive numbers.
--------------------------------------------
-5 -4 -3 -2 -1 0 1 2 3 4 5

The -3 and 3 are the same distance from 0, that being 3, so they are said to have an absolute value of 3, and it is written as |3|



OPPOSITES
Each integer (number) has an opposite. The opposite is the same distance from 0 in the opposite direction, thus, -3 is opposite to 3.

0 is neither positive or negative.

You can use greater than and less than < >symbols to compare the integers.
10 > 2
-2 > -6
-3 < -2

Adding and Substracting Integers

You can add and subtract using the number line as shown.
Start at 0 when using the number line for adding or subtracting
-3 + (-2) = ?

------------------------------------------------------------
-5 -4 -3 -2 -1 0 1 2

At 0, count 3 to the left, then add 2 additional, for -3 + (-2) = -5

Multiplying and Dividing with Integers

You need to know:
negative (-) x (-) is positive (+)

negative (-) x (+) is negative (-)

therefore:

4 x (-4) = -16
(-4) x (-4) = 16

If the result is negative -, then place in front of the number as shown, -16.
If the result is positive +, you don't place + in front of the number, 16.
When solving equations, you might see x or . for multiplication problems. Both mean 'multiply'

The number line is good to use for practice and as a reference, especially when first learning pre algebra.

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