It appears there may be a typo in your question. If you are referring to a "dewy decimal system," it is a classification system used in libraries to organize books based on subject matter. It was developed by Melvil Dewey and assigns a unique number to each book to make it easier for users to find materials.
You would find the Dewy Classification System in a Library!
5% = 0.05
dewy decemal system
Melvil Dewy
He created the Dewy Decimal system
using the dewy decimal system.
Trains would be in the 620s.
Dewy's Adventure happened in 2007.
To convert 75% to decimal divide by 100: 75% ÷ 100 = 0.75
Dewy's Adventure was created on 2007-07-26.
Dewy works at the DIY store on Sludge Street.
Dewy Moffatt has written: 'Pete's dragon' -- subject(s): Children's stories