In English, we have a variety of ways to say "approximately". There are several in Mandarin as well.
大概 (Dàgài) is pretty common
大约 (Dàyuē) is also pretty common
差不多(Chàbùduō) is literally like "less not more" and is often used for "about" but it's closer to "almost"
But the one I wanted to highlight today is a less obvious one:
左右 (Zuǒyòu) is literally "left right" but is used for "approximately" or "roughly".
It's a great example of how Chinese often uses opposites in a simple way.