Calculus is a branch of mathematics that focuses on understanding the changes between values that are related by functions of time. This involves determining how something changes, or how items add up, by breaking them into really tiny pieces. There are two different divisions of calculus; (1) differential calculus which focuses on calculating how things change from one moment to the next by dividing it in small fragments, and (2) integral calculus which focuses on understanding how much of something there is by piecing small fragments together. This area of mathematics is important to Engineering Literacy as engineering professionals frequently select and use calculus content and practices in the analysis and design of solutions to engineering problems. For example, the related mathematical applications can help one to accurately and efficiently calculate quantities like rates of flow of water from a tunnel or the rate of decay of a radioactive chemical.