Displaying columns of numbers in different units
It's important to decimal align numbers in columns when they are the same units. Decimal aligning the numbers provides an opportunity for the eye to easily identify large and small numbers within the columns without reading the numbers themselves – a visual comparison. Also, columns of numbers are usually totaled, which many times is the main point of the column of numbers.
When the numbers in a column are not the same unit, do not decimal align the numbers. It's misleading to have the numbers decimal aligned, implying that values can be compared. Instead, left align all of the numbers and include the unit with each number.
The example below illustrates this best practice. Notice that even at a glance, you see that no comparisons need to be made between the numbers. Columns of numbers in different units do not total; so each number and unit tells a part of the story, which should be summarized and explained by the presenter.