Grammar check

First things first: "Would someone like to make sure that the grammar in this sentence is correct?"

The abbreviation for "is not" is "Isn't"--the apostrophe replaces the letter "o." You have the verb "to be" twice, you only need to use it once.

Isn't solving math problems the hardest thing in the world?

Thanks so much for the answer!

You're welcome--I wish you good luck in your language studies.