Cardinal numbers indicate how many, and ordinal numbers indicate a position. For example, “two” tells us that we have two of something. “Second,” the ordinal counterpart of “two,” tells us that someone/something is second from the first in line, ranking or any other type of order. A good way to remember this distinction is that cardinal numbers “count” and ordinal numbers “order.”
A common mistake with ordinal numbers is adding “-ly” to the end: for example, making “second” “secondly.” It is not necessary, and despite the fact that we see it often, it is incorrect.
Remember, in formal writing, numbers under 10 should be written out as words!
Here are a few more examples of cardinal and ordinal numbers:
- 75 water bottles/ 75th Street
- three cats/ third cat in a row
- number-one runner/ first-place runner
- two reasons/Second, I think that…