What is the fourth book of the Old Testament?

The fourth book of the Old Testament is Numbers. It is called Numbers because it primarily presents a census of the Israelites, documenting the numbers and organization of the twelve tribes as they prepared for their journey to the Promised Land. The book also contains other important events and information, such as the rebellion of the Israelites, the appointment of leaders, and intricate laws and regulations given by God. Overall, Numbers plays a significant role in detailing the Israelites' time in the wilderness and their journey towards the fulfillment of God's promises.