What would happen if we didnt use units when measuring?

"For a measurement to make sense, it requires both a number and a unit. For example, if you told one of your friends that you had finished a homework assignment "in five", what would your friend think? Would it be five minutes or 5 hours? Maybe it was a long assignment, and you actually meant 5 days. Or maybe you meant that you wrote 5 pages. You should always express measurements in numbers and units so that their meaning is clear."

Pearson Physical Science Concepts in Action, Chapter one page 16

If you didn't use units, the answer would mean nothing and calculating would have no purpose.