# A3.12 Understanding log₁₀ reductions To keep large numbers manageable, these are often expressed using scientific notation. When calculating the magnitude of change in cell numbers, a logarithmic scale is often used. As the series demonstrates, if the log reduction is a whole integer, the numerical value equals the number of nines in the percent reduction figure. * 1 log reduction = 90% * 2 log reduction = 99% * 3 log reduction = 99.9% * 4 log reduction = 99.99% * 5 log reduction = 99.999% Similarly, the relationship can be expressed in terms of showing the number of organisms eliminated during the treatment process: * 1 log reduction = 10 times smaller * 2 log reduction = 100 times smaller * 3 log reduction = 1 000 times smaller * 4 log reduction = 10 000 times smaller * 5 log reduction = 100 000 times smaller --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/appendices/appendix-3/a3.12-understanding-log10-reductions.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.