Hello everybody!!! I need help with understanding how to find percent change.

My book gives this formula: (amount of change/original amount) * 100%

For a problem that looks like this: 80 to 100, I usually just do 20/80, which is equal to 25% (which my book's answer key tells me I am correct)

Soooo.

For a problem that reads 200 to 100, would you do 100/200, or -100/200??

And one more thing:

The formula our book tells us to use says to multiply the amount of change divided by the original amount by 100% (1.00).

What is the point of multiplying by one?? Thx Guys!

Question

Hello everybody!!! I need help with understanding how to find percent change.


My book gives this formula: (amount of change/original amount) * 100%



For a problem that looks like this: 80 to 100, I usually just do 20/80, which is equal to 25% (which my book's answer key tells me I am correct)

Soooo.

For a problem that reads 200 to 100, would you do 100/200, or -100/200??

And one more thing:

The formula our book tells us to use says to multiply the amount of change divided by the original amount by 100% (1.00).

What is the point of multiplying by one??   Thx Guys!

anonymous · Answer

200/100 * 100 = 200%. 
Multiplying by the one would not have an effect.

gorv · Answer

100%=$$=\frac{ 100 }{ 100 }=1$$

gorv · Answer

so multiply by 100

thesmartone · Answer

Welcome to OS!!

anonymous · Answer

ummm multiplying by one and 100 will give you two totally different answers......  100% = 1 not 100% =100


Thx @gorv !!!!!!!!!!!!!!!!!!!! :)))

anonymous · Answer

@mickey4691
I know but then why does the formula ask us to do so?