carelessness kills

Why i just couldn't stop making stupid careless mistakes?

I was quite confident in today's calculus test, but then i still ended up with some costly mistakes which i didn't even aware of it until the test is over.

When i realized of my costly mistakes, it's too late, there is no going back.

No more 90+ , diu, i seriously don't know what to expect now.

"A" class had their test yesterday, and guess what, their test paper was fucking easy, i can finish it in 30 minutes, but our class test paper was a bit tougher.

Carelessness kills...