Without a unit, a number doesn't tell you anything ! It's completely true that I am 910.5 old, I weigh 3,062.4, and it took me 0.04236 to drive to work this morning (because the distance is about 24,640 and there was a lot of traffic). Without any units, you still don't know anything about me. If you want to tell anybody else about anything that you measured or counted, they'll need the units along with the number.