Converting Microbial Counts to CFU

I need to know what 5.10³ breaks down to in cfu/gm on a 25gm sample

Is it 5 X 10^3?

It's hard to read the number, but if you mean 5x10^3 as Kconf mentioned, I think this is what you need:

5x10^3  =  5x1000  =  5000cfu in 25g sample

5000cfu  /  25g  =  200cfu / 1g

This is assuming you found the 5000cfu by testing the entire 25g sample.

If there are dilutions (ex: 1g sample into 10ml water), that will change the final value.

Please let us know your testing process to get a more accurate answer.