The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

All right, well to SUM up,
focus on science,
The Big Bang Theory Season 10, Episode 16

The month squared equals the
square of the SUM of the members
The Big Bang Theory Season 11, Episode 17

So to SUM up, improper instruction...
The Big Bang Theory Season 3, Episode 16

I was blown away that the square of the
hypotenuse was the SUM of the squares
The Big Bang Theory Season 10, Episode 13

Okay, so to SUM up,
one giant marble horse...
The Big Bang Theory Season 3, Episode 15