Scalar quantities can be combined using ordinary algebra because they have no direction to account for.

### Why this is right The statement is true according to the material: scalar quantities have magnitude but no direction, so they can be added or subtracted using standard algebra. The example given is calculating total daily caloric intake. ### The concept For vectors, direction can affect the result. Two forces pointing in opposite directions do not combine in the same way as two forces pointing in the same direction. Scalars avoid that directional complication, though the quantities still need compatible units and meanings before they are added. ### The concept A scalar is not simply any number: it is a measurable quantity whose description does not require direction. ### Terms - **Scalar quantity**: a measurable quantity described by magnitude alone. - **Vector quantity**: a measurable quantity described by magnitude and direction. - **Caloric intake**: energy obtained from food, as used in the material's example. ### Remember Scalar addition uses ordinary algebra, while vector addition must account for direction.