Math Question - There must be some way ...

Factual Questions
1

When I buy medical supplies (DME), although this question applies to other purchases also, I only pay a percentage of the full price (20% if it makes any difference). I believe that since I know what I paid, there should be a way of figuring out what the 100% cost is. I’m very much afraid that this involves the use of the dreaded mathematical esoteric of algebra which I was never able to get through my head. But couldn’t it be more simple?

The equation should look something like this:

fullprice = ((amountipaid)*( … ))

I know that I need to multiply because I need to increase the amountipaid by some amount.

Please suggest an equation to replace the ellipsis so I can sleep happy tonight.

Oh, yeah, no hurry.

Bob

2

WOW 731 posts in 11 years. First time I’ve noticed that.

Bob

3

If you pay 20% of the full price, then the full price is 5 times what you pay. More generally, the full price is 100/x times the price you pay, if x is the % you pay.

4

You pay (0.2)(fullprice) = (your cost) so the fullprice would yourcost divided by 0.2

5

This is not Algebra, just basic division.

Where x = the full price, c = your cost, and p = your cost’s percentage of full price:

x = c / p

So if you are paying $100, and you know that you are paying 20% of the total cost:

x = 100 / .20
x = 500

A way to think about this is recognize a percentage is just some number out of 100. So if you are paying 20 percent, you are paying 20/100 of the cost. That’s the same as 1/5.

So if you know your cost is 100, which is equivalent to 1/5 of the total cost, then it should intrinsically make sense that to find out the total cost you just need to find out what 100 is 1/5th of. So if you full price = x, then you would know that:

1/5x = 100

In an equation like that, how do you solve for x? The only thing you can do is divide by 1/5, so you end up with 100 divided by 1/5, which is 500.

6

Don’t care the 1/5 etc etc

You pay 20%
% means “per 100”

Simply divide your price by 20, then multiply by 100.

You pay 25%? Divide your price by 25, multiply by 100.

NOTE: I’ve just gone through this with a less than math literate teenager - working percentages backwards, forwards and sideways. Talking about times 5, times 8, divide by 3 etc etc that seem intuitive for the math literate just induced a blank stare.

The work our 1% method and then times 100 he got every time.

7

Amazing and everyone clearly understandable. Thanks, all.

Bob