It is. I failed a few easier (ran out of time, or got wrong results), but complete hard ones without any issues. Also, easy has stuff like "7x12", which is not

It is. I failed a few easier (ran out of time, or got wrong results), but complete hard ones without any issues. Also, easy has stuff like "7x12", which is not-so-easy (you only usually memorize multiplication tables up to 10x10). Hard, however, has things like "54/9", which is trivial and I could have done being 10 years old in an instant.