Creating a scoring metric

I am trying to create a way to rank domain between 1 and 100 based on a bunch of different metrics that range from 1 to 999,999,999. The idea is to use 3 different metrics and come up with a single number that can be accurately used to measure how good or bad a certain domain is.

One of the metrics I am using for this is AlexaRank which ranges from 1 to 999,999 (I think). 1 is obviously better. Another one would be the number of pages indexed by Google, where 1 is bad.

I think the correct way of doing this would be to give a certain base score to the range of numbers. For example, a domain with alexa rank 1 can have a base score of 49.9995, one with AR of 313 can be 46.7648 whereas one with AR of 123000 could be 24.4875 and something with AR 999000 can be 2.5478.

Does anyone know of a exponential logic that I can use for this? Really doesnt matter which language it is(prefer PH开发者_开发知识库P), I would just like some examples of the logic. Any ideas are much appreciated.

Thanks

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Alexa from 1 to 99,999,999. If one website scores 1 then it has a 100% score

Google indexed pages (you need to know how many pages the site has to extract total) if indexed is close to total than they get 100%. If indexed are 30 out of 100 total pages then they get 30% obviously

Let's say that alexa total score possible is 200 points and google total score possible is 200 points than we can do this math:

if they scored 70% in alexa then they score 140 here. If they scored 60% in Google indexed pages then they score 120. 140 + 120 = 260 total score.

There are multiple ways of doing this, you just need all the right numbers.

I hope I'm making sense lol.