"how many materials" is correct and usable in written English.
You can use it when asking what materials are required or available for a particular task. For example: "How many materials do we need for this project?".
We introduce a framework to address this problem and quantify how many materials can exist.
It is useful to evaluate what and how many materials, compounds and microorganisms are on Mars, to list what is in orbit and to identify where all these items are.
How many materials scientists are there right now?
How many materials science jobs will be created by retirements?
Total it up: How many materials science jobs will there be in the next 10 years?
At the end of your mission, or if you decide to press the "Stop Mission" button, you get a "Run Complete" summary page where they quantify how many supplies you collected, how many materials you earned, and how many zombie mobs you evaded.
Critics also object that this view does not directly answer the question of how many material objects are present for any given region, lump, or chunk.
Such mischief, whether corporate or collegiate, is how many new materials reach the home, said Toshiko Mori, a professor at the Harvard Graduate School of Design.
People have to get to the point where they no longer believe that their personal success is measured by how many new material gadgets, electronic devices, automobiles, apartments or houses, home furnishings, and exotic vacations they have.
The RInChI does not attempt to identify such mysterious entities, but it does track how many "no-structure" materials are present in the starting materials, the products and the agents.
Three teachers reportedly used the review sheets, but it wasn't clear how many knew the materials were suspect.
