If one thing can be done in m ways and another thing can be done in n ways, the two things can be done in mn ways. Example: A restaurant has 5 appetizers, 8 beverages, 9 entrees, and 6 desserts on the ...

The Nature Index 2025 Research Leaders — previously known as Annual Tables — reveal the leading institutions and countries/territories in the natural and health sciences, according to their output in ...