What is the Dewey decimal number for Masks?

There isn't a single Dewey Decimal number for "Masks" because it's too broad of a topic. It depends on what specific aspect of masks you're interested in. Here are some possibilities:

For masks as a general concept:

* 391 - Costume and personal adornment. This would cover the historical and cultural aspects of masks.

For specific types of masks:

* 745.59 - Masks, specifically covering the craft of making masks.

* 742.5 - Costume design, if you're interested in masks as part of costumes.

For masks used in specific contexts:

* 614.47 - Public health, if you're looking at masks for medical purposes.

* 792 - Theatre, if you're interested in masks used in theatrical productions.

* 791.43 - Film, if you're focusing on masks used in movies.

For specific cultures and their masks:

* 909.82 - African cultures, if you're studying African masks.

* 951 - Chinese culture, if you're studying Chinese masks.

For masks as a literary or artistic theme:

* 809.93 - Literary criticism of masks.

* 759.94 - Art, if you're looking at paintings or sculptures of masks.

To find the most relevant Dewey Decimal number, you'll need to be more specific about the type of mask or the context you're interested in.