Directed Numbers
What are Directed Numbers?
we can count things like stones,dogs,trees..etc ,for counting these objects we use natural numbers 1,2,3,4,5.... but sometimes we want to count numbers with a direction
Ex-
lets imagine about a River which remain water constant for a long period, But One day it's water level dropped so we need to express this situation with numbers. in here we can apply directed numbers. But how?
If water lavel drop we can call it as a negative Value. like (-1.5)meters
When water level Rise We can Represent it as a positive value like (+2) meters
So when we have two direction Value change we can use Directed Numbers
Ex-Temperature
water Level
financial Situations
for a Motion of an Object
examples for Directed Numbers(Integers)
+1,+2,+5,+6,+7.. -1,-2,-3....
Def for Directed Numbers
"All the numbers that are written with a positive or negative sign to
indicate not only their magnitude but also one of two directions which
are opposite to each other are defined as directed numbers."
How to Identify the sign of a Directed Number
when someone didn't mention about sign of a number we consider it as a positive number.
sign is always placed in left side of the number
ex- -4,+3,-7.5
+3-4+12 (in this expression -sign for 4 and 7.5,+sign for 3 )
Addition and subtraction of Directed Numbers
rule 1
when we have Addition or subtration
If
signs are eqal add the numbers without considering their signs and put answer. the sign of the answer should remain same.
ex- (1) +13+2
= +15
(2) -10-5
= -15
(3) 12+8
= +20
rule 2
when we have Addition or subtration
If
signs are not eqal subtract the numbers without considering their signs and put answer.the sign of the answer should be the sign of Largest number
ex- (1) +13-2
= +11(largest number is 13 it's sign is +)
(2) -10+5(largest number is 10 it's sign is -)
= -5
(3) 12-8(largest number is 12 it's sign is +)
= +4
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| Photo by Tyler Easton on Unsplash |
