The number of objects should be very small and focused on key concepts.

A number of exhibitions focus on artists who are relatively young and unknown.

A number of the films focus on the Middle East.

A significant number of care farms focus on organic farming.

A number of recent works have focused on this exact problem.

A huge number of recent research studies have focused on an effective solution for waste treatment.

A growing number of titles focus on health, nutrition, history, and science.

A large number of research groups focus on topics related to human computer interaction.

A significant number of these projects have focused on family law.

This summer, a number of events will focus on this debate.